Thanks for the info on the Irwin tools. I've just had a look on e-Bay and one of the 5-piece sets does include a 13mm tool which will fit the Fiesta caliper bolts.

Yes my thanks too, never used them but there have been times when they would have saved me a heap of grief and skinned knuckles, and anyone in earshot from my reaction.

Removing the gearbox from a Toyota Supra many years ago put me onto impact sockets, i'd struggled with combi spanners and normal sockets on the top bell housing bolt that would not shift, 14mm can still see it but very shallow head, almost rounded off and i'm scratching me bonce...someone lent me a 14mm impact 6 sider...i slid underneath and with about 3ft of extensions and a universal i got the socket on the bolt, click, undone no probs.

Wouldn't be without them now, not only do they not slip but being heavy if you use an impact extension and an old click type torque wrench as your ratchet the amount of control and feel you have over the moment of release of the stuck bolt is superb and satisfying and ultimately less painful, none of that slight twist (almost like play) you get with lighter extensions and sockets the they suddenly give and then you curse as yet another knuckle bites the dust.