What is this tool for?

[picky]

So, what is this for? It came with a job lot of SU carburettors, although I don't think it has anything to do with carbs. It is approx 1 1/4" diameter, and has a small slot at the end, only one slot which is unusual. If its home made then it has been made quite well, looks like mild steel with a welded handle. Hollow all the way through nothing inside:

[MarkyB]

I'd say it's for adjusting something probably with a tab sticking out and a lock-nut on top.
Shame it's home made, a company name might narrow it down a bit.

[lambrettalad]

^^^^^ maybe for holding a woodruff key e.g. like the magneto on a scooter ?

[picky]

Woodruff key is likely I guess, I wonder if it is just for turning a crankshaft while assembling the engine? Seems a bit over the top to make a tool for it though.

[katy]

Got dimensions?

[picky]

Internal diameter is 1 3/8", and tube is 3" long.

The slot is 1/4" wide and 1/2" deep, and appears to have been stamped out, rather than being done with a hacksaw which I would have expected from a home made tool.

No numbers or markings on it. Evidence of paint on the inside, black or dark green. I am now pretty convinced it is for rotating the crankshaft of an engine while setting up camshaft timing etc. Handy tool if it fits A series, I will treat it to some spray paint if it does!