Robin,
Check out Reid Tool.
Something like this:
http://www.reidtool.com/store/store/...dProducts.asp?
idCategory=6413 is probably what you want. Although the page I pasted is
for Inch series, they offer metric also. We use these things all over the
place for adjustments. The handle disengages with a pull up, so they work
well where you only have limited radial clearance.

Yeah, that's what I use if there's enough space, they're great.
--
Cheers,

--Mitch