Tool to open/close Isolating Valve

[yottie]

My toilet isolating valve has been fitted in a pretty difficult place to access, I seem to remember seeing a tool consisting of a screwdriver blade inside a tube (helps centering etc onto valve)?
Any advice appreciated.

 

[Burnerman]

Facom do screwdrivers that can clutch the screw head to give you an easy start but I doubt if you'll find something that will do exactly what you need.....any mileage in using a length of overflow pipe or similar as a guide?
John