The invention provides a compound of the formula (I): or a salt, N-oxide, tautomer or solvate thereof, wherein X is CR 5 or N; each of Q 1 and Q 2 is a carbon atom; Q 3 is selected from S and CH; Q 4 is selected from CR 2 and S; provided that one of Q 3 and Q 4 is S and the other of Q 3 and Q 4 is not S; wherein when Q 3 is S, there is a double bond between Q 1 and Q 4 and a double bond between Q 2 and the adjacent ring nitrogen atom N; and when Q 4 is S, there is a double bond between Q 1 and Q 2 , and a double bond between Q 3 and the adjacent ring nitrogen atom N; A is a bond or -(CH 2 ) m -(B) n -; B is C=O, NR g (C=O) or O(C=O) wherein R 1 is hydrogen or C1_4 hydrocarbyl optionally substituted by hydroxy or C 1-4 alkoxy; m is 0, 1 or 2; n is 0 or 1; R ° is hydrogen or, together with NR g when present, forms a group -(CH 2 ) p - wherein p is 2 to 4; R 1 is hydrogen, a carbocyclic or heterocyclic group having from 3 to 12 ring members, or an optionally substituted C 1-8 hydrocarbyl group; R 2 is hydrogen, halogen, methoxy, or a C 1-4 hydrocarbyl group optionally substituted by halogen, hydroxyl or methoxy; R 3 and R 4 together with the carbon atoms to which they are attached form an optionally substituted fused carbocyclic or heterocyclic ring having from 5 to 7 ring members of which up to 3 can be heteroatoms selected from N, 0 and S; and R 5 is hydrogen, a group R 2 or a group R 10 wherein R 10 is as defined in the claims.The compounds have activity as inhibitors of cyclin dependent kinases, glycogen synthase kinases and Aurora kinases.