Done a bit of Googling , it appears to be a 10mm Ribe socket, which looks like a torx but has squared off edges.
Fingers crossed Dazza, do the bolts look like I described?
Can see the valve to piston contact on top of the pistons!
Yep - Are the cams out of the head? If so put some petrol around the valves to see which ones leak.Can see most of the inlet valves are bent from the pics but they all need removing to check properly