A combination comprising an ancillary agent and a compound of the formula: or salts or tautomers or N-oxides or solvates thereof; wherein the ancillary agent is selected from: (a) a monoclonal antibody to a cell surface antigen; or (b) an alkylating agent wherein said alkylating agent is selected from nitrogen mustards; nitrosoureas; bifunctional alkylating agents having a bis-alkanesulfonate group; and aziridine compounds; and wherein the alkylating agents are other than mitomycin C or cyclophosphamide: or (c) an anticancer agent selected from COX-2 inhibitors, HDAC inhibitors, DNA methyltransferase (methylase) inhibitors and proteasome inhibitors; or (d) a further CDK inhibitor; and (e) an anti-androgen including an anti-oestrogen; Y is a bond or an alkylene chain of 1, 2 or 3 carbon atoms in length; R 1 is a carbocyclic or heterocyclic group having from 3 to 12 ring members, wherein the carbocyclic or heterocyclic group is unsubstituted or substituted by one or more substituent groups R 10; or a C 1-8 hydrocarbyl group optionally substituted by one or more substituents selected from fluorine, hydroxy, C 1-4 hydrocarbyloxy, amino, mono- or di-C 1-4 hydrocarbylamino, and carbocyclic or heterocyclic groups having from 3 to 12 ring members wherein the carbocyclic or heterocyclic groups are unsubstituted or substituted by one or more substituent groups R 10; R 2 is hydrogen or methyl; R 3 is selected from non-aromatic carbocyclic and heterocyclic groups having from 3 to 12 ring members, wherein the carbocyclic or heterocyclic group is unsubstituted or substituted by one or more substituent groups R 10; and R 10 is selected from halogen, hydroxy, trifluoromethyl, cyano, nitro, carboxy, amino, mono- or di-C 1-4 hydrocarbylamino, carbocyclic and heterocyclic groups having from 3 to 12 ring members; a group R a -R b wherein R a is a bond, O, CO, X 1 C(X 2), C(X 2)X 1, X 1 C(X 2)X 1, S, SO, SO 2, NR c, SO 2 NR c or NR c SO 2; and R b is selected from hydrogen, carbocyclic and heterocyclic groups having from 3 to 12 ring members, and a C 1-8 hydrocarbyl group optionally substituted by one or more substituents selected from hydroxy, oxo, halogen, cyano, nitro, carboxy, amino, mono- or di-C 1-4 hydrocarbylamino, carbocyclic and heterocyclic groups having from 3 to 12 ring members; R c is selected from hydrogen and C 1-4 hydrocarbyl; and X 1 is O, S or NR c and X 2 is =O, =S or =NR c; and provided that where the substituent group R 10 comprises or includes a carbocyclic or heterocyclic group, the said carbocyclic or heterocyclic group may be unsubstituted or may itself be substituted with one or more further substituent groups R 10 and wherein (a) such further substituent groups R 10 include carbocyclic or heterocyclic groups, which are not themselves further substituted; or (b) the said further substituents do not include carbocyclic or heterocyclic groups but are otherwise selected from the groups listed above in the definition of R 10. (a) a monoclonal antibody to a cell surface antigen; or (b) an alkylating agent wherein said alkylating agent is selected from nitrogen mustards; nitrosoureas; bifunctional alkylating agents having a bis-alkanesulfonate group; and aziridine compounds; and wherein the alkylating agents are other than mitomycin C or cyclophosphamide: or (c) an anticancer agent selected from COX-2 inhibitors, HDAC inhibitors, DNA methyltransferase (methylase) inhibitors and proteasome inhibitors; or (d) a further CDK inhibitor; and (e) an anti-androgen including an anti-oestrogen; Y is a bond or an alkylene chain of 1, 2 or 3 carbon atoms in length; R 1 is a carbocyclic or heterocyclic group having from 3 to 12 ring members, wherein the carbocyclic or heterocyclic group is unsubstituted or substituted by one or more substituent groups R 10; or a C 1-8 hydrocarbyl group optionally substituted by one or more substituents selected from fluorine, hydroxy, C 1-4 hydrocarbyloxy, amino, mono- or di-C 1-4 hydrocarbylamino, and carbocyclic or heterocyclic groups having from 3 to 12 ring members wherein the carbocyclic or heterocyclic groups are unsubstituted or substituted by one or more substituent groups R 10; R 2 is hydrogen or methyl; R 3 is selected from non-aromatic carbocyclic and heterocyclic groups having from 3 to 12 ring members, wherein the carbocyclic or heterocyclic group is unsubstituted or substituted by one or more substituent groups R 10; and R 10 is selected from halogen, hydroxy, trifluoromethyl, cyano, nitro, carboxy, amino, mono- or di-C 1-4 hydrocarbylamino, carbocyclic and heterocyclic groups having from 3 to 12 ring members; a group R a -R b wherein R a is a bond, O, CO, X 1 C(X 2), C(X 2)X 1, X 1 C(X 2)X 1, S, SO, SO 2, NR c, SO 2 NR c or NR c SO 2; and R b is selected from hydrogen, carbocyclic and heterocyclic groups having from 3 to 12 ring members, and a C 1-8 hydrocarbyl group optionally substituted by one or more substituents selected from hydroxy, oxo, halogen, cyano, nitro, carboxy, amino, mono- or di-C 1-4 hydrocarbylamino, carbocyclic and heterocyclic groups having from 3 to 12 ring members; R c is selected from hydrogen and C 1-4 hydrocarbyl; and X 1 is O, S or NR c and X 2 is =O, =S or =NR c;