Bolts for wheel adaptors

Does anyone know where I can get the M12 1.5 pitch allen key bolts which attach PCD adapters to a Mk1 Golf hub?  I guess they are 25 or 30mm threads.

All help appreciated!

Cheers

In case anyone is also looking for the bolts that fix adapters to hubs I have now found them.  After calling quite a few places I got them from Balls Fasteners in Cheltenham, M12 1.5 pitch 25mm full thread high tensile (12.9 gauge) with a shallow 10mm allen cap.