The screw head is a raised triangle in the middle but the 3 corners are close to the edge of the countersink. So it needs something similar to a valve tool but with 3 points. Where can I find one?

I probably have one, my brother in law is a tool salesman, if you know its name I can probably get one for you?

It’s called a insert bit

http://www.amazon.co.uk/100-PIECE-SCREWDRIVER-SECURITY-BIT/dp/B0047WL5GK

I have a kit a bit like that, so probably worth a punt?

I don’t think they will work as the gap between the 3 corners and the countersunk bit outer.

Can’t really picture it but if it as a raised triangle can you use a normal hex/bi-hex socket on the corners?

check out the 2 sets in green trays and the one in the red box here: http://www.toolstation.com/shop/Power+Tool+Accessories/Bit+Sets/d80/sd650

red box one is also sold as a sealey product if you don’t have a toolstation near you.

I’ll get a picture one sec

Can anyone help?

I’d get an old buggered screwdriver and modify it to fit the hole.

I’ll give that a go

Beat the shit out of it with a blunt screwdriver

Haha i’ve got the solution. As the screw is taking any strain or tight I just worked it round with a small screw driver…

Cut a slot in the top help unscrewing out nextime