FORM -2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10) LAUNDRY TREATMENT COMPOSITIONS HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India The following specification particularly describes the nature of the invention and the manner in which it is to be performed. LAUNDRY TREATMENT COMPOSITIONS Technical Field The present invention relates to compositions comprising a substituted polysaccharide of the kind comprising a benefit agent and a deposition aid for deposition of the benefit agent onto a substrate, and a silicone. These compositions^are suitable, for example, for use as laundry treatment compositions or as components thereof. It further relates to a method of depositing a silicone from solution or dispersion, onto a substrate by means of such a composition. Background of the Invention The deposition of a benefit agent onto a substrate, such as a fabric, is well known in the art. In laundry applications typical "benefit agents" include fabric softeners and conditioners, soil release polymers, sunscreens; and the like. Deposition of a benefit agent is used, for example, in fabric treatment processes such as fabric softening to impart desirable properties to the fabric substrate. Conventionally, the deposition of the benefit agent has had to rely upon the attractive forces between the oppositely charged substrate and the benefit agent. Typically this requires the addition of benefit agents during the rinsing step of a treatment process so as to avoid adverse effects from other charged chemical species present in the treatment compositions. For example, cationic fabric conditioners are incompatible with anionic surfactants in laundry washing compositions. Such adverse charge considerations can place severe limitations upon the inclusion of benefit agents in compositions where an active component thereof is of an opposite charge to that of the benefit agent. For example, cotton is negatively charged and thus requires a positively charged benefit agent in order for the benefit agent to be substantive to the cotton, i.e. to have an affinity for the cotton so as to absorb onto it. Often the substantivity of the benefit agent is reduced and/or the deposition rate of the material is reduced because of the presence of incompatible charged species in the compositions. However, in recent times, it has been proposed to deliver a benefit agent in a form whereby it is substituted onto another chemical moiety which increases its affinity for the substrate in''question. Prior Art WO-A-98/00500 discloses detergent compositions comprising a peptide or protein deposition aid having a high affinity for fibres or a surface, and a benefit agent attached/adsorbed to the deposition aid. However, this deposition aid does not change chemically such as to increase its affinity for the substrate during the treatment process. GB-A-1 031 484 discloses stable aqueous dispersions of elastic copolymers which can be converted to cross-linked polymers by the action of heat or acid. They can be used to produce films or covering layers. However, none of the compounds has a benefit agent attached to the deposition enhancing part. There is no disclosure of using these materials in methods of laundry or fabric care. US-A-5 730 760 discloses a process of fabric washing in which a dye redeposition inhibitincpagent is used. The dye redeposition inhibiting polymer used is of a specific type, being produced by polymerising, for example, vinylester monomers. There is not any mention of materials having any surface substantive properties nor is there a description of any reaction by which such surface substantive properties increase during use. WO-A-92/13114 discloses hair fixative polymers which form a film after application. The polymers are fundamentally different from those of the present invention in that they do not comprise a deposition part attached to a benefit agent. The polymeric material has no particular affinity for hair - it is just applied onto it. There is certainly no mention of a reaction which increases the affinity. Any reaction which occurs leads to the cross-linking of polymer and the formation of film. It is not disclosed that the polymers should be water-soluble of dispersible - they are normally dissolved in an inert carrier such as alcohol. WO-A-95/35087 discloses a hair fixative amphoteric polymer composition. It is insoluble in water but can be solubilised by use of neutralisers or solubilising alcohol/water mixtures. The polymers do not to undergo any reaction which increases their affinity for hahv There is no benefit agent attached to the polymer. WO-A-98/29528 discloses cellulose ethers in which some substituents are (poly)alkoxylated, analogues of the latter in which the (poly)alkoxylated groups are terminated with a cationic moiety in the form of a quaternary ammonium group, and cellulose ethers in which some substituents are carboxylic acids in the salt form (i.e. the materials are essentially carboxymethylcellulose variants). None of these substituents in any variant is of a kind which would undergo a chemical change to enhance fabric affinity. WO-A-99/14245 discloses laundry detergent compositions containing cellulosic based polymers to provide appearance and integrity benefits to fabrics. These polymers are cellulosic polymers in which the saccharide rings have pendant oxygen atoms to which substituents 'R' are bonded, i.e. they are attached to the rings via an ether linkage. The groups 'R' can be hydrogen, lower alkyl or alkylene linkages terminated by carboxylic acid, ester or amide groups. Optionally, up to five alkyleneoxy groups may be interspersed between the groups are the respective oxygen atom. None of the pendant groups is a benefit agent group. However, at least some of these groups may undergo a chemical change such as hydrolysis, in the wash liquor. However no such change would result in an increased affinity for the fabric. On the contrary, because the "ester" group is configured with the carbonyl group closer to the polysaccharide than the oxygen atom (i.e. esters of carboxyalkyl groups), any hydrolysis will result in free acid substituents which will actually result in an increase in solubility and therefore, a decrease in affinity for the fabric. WO-A-99/14295 discloses structures analogous to those described in WO-A-99/14245 but in one alternative, the substituents 'R' together with the oxygen on the saccharide ring, constitute pendant half-esters of certain dicarboxylic acids. A single example of such a material is given. Again, no pendant group is a benefit agent group. However, the dicarboxylic acid half-esters would tend to hydrolyse in the wash liquor and thereby increase affinity of the material for a cotton fabric. However, first, this mechanism of WO 03/020819 PCT7EP02/09228 action or behaviour is not mentioned. Second, the hydrolysis rate of such dicarboxylic acids half esters is not as great as that of esters of monocarboxylic acids (which are not disclosed or claimed in WO-A-99/14295). Third, the degree of substitution for this variant is specified as being from 0.001 to 0.1. This is so low as to make the enhancement of fabric affinity too low to be worthwhile for this mechanism of action. Fourth, the structures described and claimed insofar as they have such half ester substituents, must also have substituents of the type which are carboxyalkyi groups or esters thereof, i.e. of the type also described in W0-A-99/14245. In the latter (ester) case, these would hydrolyse to the free acid form. The degree of substitution of the latter (0.2 to 2) is considerably higher than for the half-ester groups and the resultant increase in solubility would easily negate any enhanced affinity for the fabric by hydrolysis of the half-ester groups. WO-A-00/18861 provides a water-soluble or water-dispersible material for deposition onto a substrate during a treatment process, wherein the material comprises: (i) a deposition enhancing part having a polymeric backbone; and (ii) a benefit agent group attached to the deposition enhancing part by a hydrolytically stable bond; such that the material undergoes during the treatment process, a chemical change which does not involve the hydrolytically stable bond and by which change the affinity of the material onto the substrate is increased. The preferred materials are substituted polysaccharides. WO-A-00/18861 mentions as possible benefit groups, lubricants, ironing aids and fabric softeners. However, it is known that silicone materials are especially useful agents for delivering this kind of benefit Our UK patent application no. 0121148.1, unpublished at the priority date of this application, describes and claims a substituted Si^ linked polysaccharide having covalently bonded on the polysaccharide moiety thereof, at least one deposition enhancing group which undergoes a chemical change in water at a use temperature to increase the affinity of the substituted polysaccharide to a substrate, the substituted polysaccharide further comprising one or more independently selected silicone chains. We have now found that these substituted polysaccharides can be incorporated in compositions containing a silicone perse to enhance deposition of the silicone. Definition of the Invention A first aspect of the present invention provides a composition (e.g. a chemical composition or a laundry treatment composition) comprising a silicone and a substituted polysaccharide comprising p -M linkages having covalently bonded on the polysaccharide moiety thereof, at least one deposition enhancing group which undergoes a chemical change in water at a use temperature to increase the affinity of the substituted polysaccharide to a substrate, the substituted polysaccharide further comprising one or more independently selected silicone chains. A second aspect of the present invention provides a method for depositing a silicone onto a substrate, the method comprising, contacting in an aqueous medium, the substrate and a composition according to the first aspect of the invention. A further aspect of the invention provides the use of a composition according to the first aspect of the invention to enhance the softening benefit of a laundry treatment composition on a substrate. Detailed Description of the Invention THE SILICONE Silicones are conventionally incorporated in laundry treatment (e.g. wash or rinse) compositions to endow antifoam, fabric softening, ease of ironing, anti-crease and other benefits. Any type of silicone can be used to impart the lubricating property of the present invention however, some silicones and mixtures of silicones are more preferred. Typical incfusion levels are from 0.01% to 25%, preferably from 0.1% to 5% of silicone by weight of the total composition. Suitable silicones include: - non-volatile silicone fluids, such as poly(di)alkyl siloxanes, especially polydimethyl siloxanes and carboxylated or ethoxylated varients. They may be branched, partially cross-linked or preferably linear. - aminosilicones, comprising any organosilicone having amine functionality for example as disclosed in EP-A-459 821, EP-A-459 822 and WO 02/29152. They may be .blanched,.partially cross-linked or,preferably-linear. - any organosilicone of formula H-SXC where SXC is any such group hereinafter defined, and derivatives thereof. -reactive silicones and phenyl silicones The choice of molecular weight of the silicones is mainly determined by processability factors. However, the molecular weight of silicones is usually indicated by reference to the viscosity of the material. Preferably, the silicones are liquid and typically have a viscosity in the range 20 cStokes to 300,000 cStokes. Suitable silicones include dimethyl, methyl (aminoethylaminoisobutyl) siloxane, typically having a viscosity of from 100 cStokes to 200 cStokes with an average amine content of ca. 2mol% and, for example; Rhodorsil Oil 21645, Rhodorsil Oil Extrasoft and Wacker Finish 1300. More specifically, materials such as polyalkyl or polyaryl silicones with the following structure can be used : The alkyl or aryl groups substituted on the siloxane chain (R) or at the ends of the siloxane chains (A) can have any structure as long as the resulting silicones remain fluid at room temperature. R preferably represents a phenyl, a hydroxy, an alkyl or an aryl group. The two R groups on the silicone atom can represent the same group or different groups. More preferably, the two R groups represent the same group preferably, a methyl, an ethyl, a propyl, a phenyl or a hydroxy group, "q" is preferably an integer from about 7 to about 8,000. "A" represents groups which block the ends of the silicone chains. Suitable A groups include hydrogen, methyl, methoxy, ethoxy, hydroxy, propoxy, and aryloxy. Preferred alkylsiloxanes include polydimethyl siloxanes having a viscosity of greater than about 10,000 centistokes (est) at 250C; and a most preferred silicone is a reactive silicone, i.e. where A is an OH group. Suitable methods for preparing these silicone materials are disclosed in US-A-2,826,551 and US-A-3,964,500. Other useful silicone materials include materials of the formula: wherein x and y are integers which depend on the molecular weight of the silicone, the viscosity being from about 10,000 (est) to about 500,000 (est) at 25°C. This material is also known as "amodimethicone". Other silicone materials which can be used, correspond to the formulae: wherein G is selected from the group consisting of hydrogen, phenyl, OH, and/or d* 25 alkyl; a denotes 0 or an integer from 1 to 3; b denotes 0 or 1; the sum of n + m is a wherein (1) the symbols Z are identical or different, represent R1, and/or V; (2) R1, R2and R3 are identical or different and represent a monovalent hydrocarbon radical chosen from the linear or branched alkyl radicals having 1 to 4 carbon atoms, the linear or branched alkoxy radicals having 1 to 4 carbon atoms, a phenyl radical, preferably a hydroxy radical, an ethoxy radical, a methoxy radical or a methyl radical; and (3) the symbols V represent a group of stericalty hindered piperidinyl functions chosen from number from 1 to about 2,000; R1 is a monovalent radical of formula CpH2pL in which p is an integer from 2 to 8 and L is selected from the group consisting of wherein each R2 is chosen from the group consisting of hydrogen, phenyl, benzyl, a 5 -«saturated43>drocait>onr-adieal,-andeachA%dera©les»a'OompatibleaFHon,»e.g;a'halide ion; and wherein R3 denotes a long chain alkyl group; and f denotes an integer of at least about 2. wherein n and m are the same as before. 15 Another silicone material which can be used, has the formula: For the groups of formula II - R4 is a divalent hydrocarbon radical chosen from - linear or branched alkylene radical, having 2 to 18 carbon atoms; - linear or branched alkyiene-carbonyl radical where the alkylene part is linear or branched, comprising 2 to 20 carbon atoms; - linear or branched alkylene-cycolhexyiene where the alkylene part is linear or branched, comprising 2 to 12 carbon atoms and the cydohexylene comprises an OH group and possibly 1 or 2 alkyl radicals having 1 to 4 carbon atoms; - the radicals of the formula -R7-0-R7 where the R7 radical is identical or different represents an alkylene radical having 1 to 12 carbon atoms; - the radicals of the formula -R7-0-R7 where the R7 radical is as indicated previously and one or both are substituted by one or two OH groups; --the radicals of the formula -R7-COO-R7 where the -R7 radicals are as indicated previously; - the radicals of formula R8 -0-R9-0-CO-R8 where the R8 and R9 radicals are identical or different, represent alkylene radicals and have 2 to 12 carbon atoms and the radical R9 is possibly substituted with a hydroxyl radical; - U represents -O- or-NR10-, R10 is a radical chosen from a hydrogen atom, a linear or branched alkyl radical comprising 1 to 6 carbon atoms and a divalent radical of the formula: where R4 is as indicated previously, R5 and R6 have the meaning indicated below et R11 represents a divalent aikylene radical, linear or branched, having 1 to 12 carbon atoms, one of the valent bonds (one of R11) is connnected to an atom of-NR10-, the other (one of R4) is connected to a silicone atom; -the radical R5 is identical or different .chosen from the linear or branched alkyl radicals having 1 to 3 carbon atoms and the phenyl radical; -trie radfcalR6 represents a hydrogen radlcal or the R5radlcal or O. R"4 is chosen from a trivalent radical of the formula: where m represents a number between 2 and 20, and a trivalent radical of the formula: For the groups of formula (111): where p represents a number between 2 and 20; - U represents-O- or NR12, R12 is a radical chosen-frem-a hydrogen-atom, a linear or branched alkyl radical comprising 1 to 6 carbon atoms; - R and Rhave the same meaning as proposed for formula (U); and (4) - the number of units nSi without group V comprises between 10 and 450 - the number of units flSi with group V comprises between 1 and 5, - 0