A compound of formula I: a tautomer thereof, or a pharmaceutically acceptable salt of said compound or tautomer, wherein: R 1b, R 1c, R 1d and R 1e are each independently selected from hydrogen and optionally substituted C 1 -C 6 alkyl; R 1a, R 1f and R 1g are each independently selected from hydrogen, fluorine, cyano, hydroxyl, amino, optionally substituted C 1 -C 6 alkyl and optionally substituted C 1 -C 6 alkoxy, or R 1a is linked to R 2 to form a pyrrolidine ring; R 2 is optionally substituted C 1 -C 3 alkyl, or together with R 3 forms an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heterocyclyl or heteroaryl ring, or R 2 together with R 1a forms a pyrrolidine ring; R 3 is an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heteroaryl or aryl ring, or R 3 together with R 2 forms an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heterocyclyl or heteroaryl ring; L represents a covalent bond or C 1 -C 3 alkylene, or forms part of the heterocyclyl or heteroaryl ring formed by R 2 and R 3; R 3 or the ring formed by R 2 and R 3 is optionally substituted with one to four -Q 1 -(R 4) n moieties, wherein each occurrence of -Q 1 (R 4) n is the same or different, wherein; n is 0 or 1; Q 1 is selected from halogen, cyano, -CONR 5 R 6, -C 1 -C 6 alkyl and a covalent bond; R 4 is a 3 to 10-membered, monocyclic or bicyclic, heterocyclyl, heteroaryl, aryl or cycloalkyl ring, which is optionally substituted with 1 to 4 groups, each independently selected from halogen, cyano, oxo, nitro, -OR 8, -SR 8, -NR 8 R 9, -CONR 8 R 9, -NR 8 COR 9, -COR 8, -C OR 8, - SO 2 R 8, -SO 2 NR 8 R 9, -NR 8 SO 2 R 9, -NR 8 C OR 9, optionally substituted -C 1 -C 6 alkyl, optionally substituted -C 1 -C 6 alkoxy and -Q 2 -R 8; Q 2 is selected from a covalent bond, an oxygen atom, -CO- and C 1 -C 6 alkylene; R 8 and R 9 are each independently selected from hydrogen, C 1 -C 6 alkyl, optionally substituted C 3 -C 10 heterocyclyl, optionally substituted C 5 -C 10 heteroaryl, optionally substituted C 5 -C 10 aryl, and C 3 -C 6 cycloalkyl; wherein the optional substituents for the heterocyclyl, heteroaryl and aryl rings are selected from fluorine, chlorine, oxo, cyano, C 1 -C 3 alkyl and C 1 -C 3 alkoxy; R 5 and R 6 are each independently selected from hydrogen and C 1 -C 6 alkyl; and wherein the alkyl and alkoxy groups of R 1a, R 1b, R 1c, R 1d, R 1e, R 1f, R 1g, R 2 and R 4 are optionally substituted with one to four substituents, each independently selected from halogen, hydroxy and cyano. R 1b, R 1c, R 1d and R 1e are each independently selected from hydrogen and optionally substituted C 1 -C 6 alkyl; R 1a, R 1f and R 1g are each independently selected from hydrogen, fluorine, cyano, hydroxyl, amino, optionally substituted C 1 -C 6 alkyl and optionally substituted C 1 -C 6 alkoxy, or R 1a is linked to R 2 to form a pyrrolidine ring; R 2 is optionally substituted C 1 -C 3 alkyl, or together with R 3 forms an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heterocyclyl or heteroaryl ring, or R 2 together with R 1a forms a pyrrolidine ring; R 3 is an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heteroaryl or aryl ring, or R 3 together with R 2 forms an optionally substituted 5 to 10-membered, monocyclic or bicyclic, heterocyclyl or heteroaryl ring; L represents a covalent bond or C 1 -C 3 alkylene, or forms part of the heterocyclyl or heteroaryl ring formed by R 2 and R 3; R 3 or the ring formed by R 2 and R 3 is optionally substituted with one to four -Q 1 -(R 4) n moieties, wherein each occurrence of -Q 1 (R 4) n is the same or different, wherein; n is 0 or 1; Q 1 is selected from halogen, cyano, -CONR 5 R 6, -C 1 -C 6 alkyl and a covalent bond; R 4 is a 3 to 10-membered, monocyclic or bicyclic, heterocyclyl, heteroaryl, aryl or cycloalkyl ring, which is optionally substituted with 1 to 4 groups, each independently selected from halogen, cyano, oxo, nitro, -OR 8, -SR 8, -NR 8 R 9, -CONR 8 R 9, -NR 8 COR 9, -COR 8, -C OR 8, - SO 2 R 8, -SO 2 NR 8 R 9, -NR 8 SO 2 R 9, -NR 8 C OR 9, optionally substituted -C 1 -C 6 alkyl, optionally substituted -C 1 -C 6 alkoxy and -Q 2 -R 8; Q 2 is selected from a covalent bond, an oxygen atom, -CO- and C 1 -C 6 alkylene; R 8 and R 9 are each independently selected from hydrogen, C 1 -C 6 alkyl, optionally substituted C 3 -C 10 heterocyclyl, optionally substituted C 5 -C 10 heteroaryl, optionally substituted C 5 -C 10 aryl, and C 3 -C 6 cycloalkyl; wherein the optional substituents for the heterocyclyl, heteroaryl and aryl rings are selected from fluorine, chlorine, oxo, cyano, C 1 -C 3 alkyl and C 1 -C 3 alkoxy; R 5 and R 6 are each independently selected from hydrogen and C 1 -C 6 alkyl; and wherein the alkyl and alkoxy groups of R 1a, R 1b, R 1c, R 1d, R 1e, R 1f, R 1g, R 2 and R 4 are optionally substituted with one to four substituents, each independently selected from halogen, hydroxy and cyano.