A quinazoline derivative of formula I wherein X1 is O or N (R7) in which R7 is hydrogen or (C1-8) alkyl； p is 0, 1, 2 or 3； each R1 group, which may be the same or different, is selected from halogen, trifluoromethyl, cyano, hydroxy, mercapto, amino, (C1-8) alkyl, (C2-8) alkenyl, (C2-8) alkynyl, (C1 -6), (C2-6) alkenyloxy, (C2-6) alkynyloxy, (C1-6) alkyl thio, (C1-6) sulfinyl, (C1-6) sulfonyl, (C1-6) alkyl and amino di- [(C 1-6) alkyl] amino, or of a group of the formula: Q1-X2- in which X2 is a direct bond or is selected from O, S, SO, SO2, N (R8), CO, CON (R8), N (R8) CO, OC (R8) 2 and N (R8) C (R8) 2, in which each R8 is hydrogen or (C1-8) alkyl, and Q1 is aryl, aryl-alkyl (C1-6), cycloalkyl (C3-8), cycloalkyl (C3-8) -alkyl (C1-6), cycloalkenyl (C3-8), cycloalkenyl (C3-8) -alkyl (C1-6), heteroaryl, heteroaryl (C1-6) alkyl, heterocyclyl or heterocyclyl (C1-6) alkyl, and in which any aryl, cycloalkyl (C3-8), cycloalkenyl (C3-8), heteroaryl or heterocyclyl group in an R1 substituent optionally carries 1, 2 or 3 substituents, which may be the same or different, select two of halogen, trifluoromethyl, cyano, nitro, hydroxy, amino, carboxy, carbamoyl, ureido, (C1-8) alkyl, (C2-8) alkenyl, (C2-8) alkynyl, (C1-6) alkoxy, alkenyloxy ( C2-6), alkyloxy (C2-6), alkyl (C1-6) thio, alkyl (C1-6) sulfinyl, alkyl (C1-6) sulfonyl, alkyl (C1-6) amino, di- [alkyl (C1 -6)] amino, (C1-6) alkoxycarbonyl (C2-6) alkanoyl, (C2-6) alkanoyloxy, N-(C1-6) alkylcarbamoyl, N, N-di- [C1- (alkyl-) 6)] carbamoyl, (C2-6) alkanoyl, N-(C1-6) -alkanoyl (C2-6) amino, N-(C1-6) alkyl ureido, N'-(C1-6) alkyl ureido , N ', N'-di- [C1-6 alkyl] ureido, N, N'-di- [C1-6 alkyl] ureido, N, N', N'-tri- [C1 alkyl -6)] ureido, N-C 1-6 alkyl sulfamoyl, N, N-di- [C 1-6 alkyl] sulfamoyl, C 1-6 alkanesulfonylamino and N-C 1-6 alkyl alkano (C1-6) sulfonylamino, or of a group of the formula: -X3-R9 in which X3 is a direct bond or is selected from O and N (R10), in which R10 is hydrogen or (C1-8) alkyl , and R9 is halogen
