Missing Campag Veloce 10 Spd B-Screw

I'm missing the B-Screw in my Veloce Derailleur, does anybody have an idea about the thread pitch / bolt dimensions so that I could source a replacement? Thanks in advance!

If you're in london, clerkenwell screws are happy to let you try a load in my experience, only once been there and not found what I needed.

http://www.gbcycles.co.uk/p/94680/Campagnolo-Rear-Derailleur-Set-Stop-Screws-RD-RE110?kw=&fl=1000&ci=44622668222&network=pla&gclid=CjwKCAjw6ZLOBRALEiwAxzyCW9ntpun7wDXoUAJ99b1FFkjgPiz61ofwNMvCIzKfoGa4DrhKQjveDhoChZsQAvD_BwE

@Tenners In Bristol at the mo, but in London next weekend, so thanks for the tip.

@mustardbeak I think those are the limit screws, so they are slightly different. I took one out to see if it fit and it was too short. I actually called GB a few days ago - but it's not a part they stock.

Sorry misread the original post! I can take the one off my wife's bike this weekend and measure it with calipers if that helps?

@mustardbeak Well it would be really helpful if not too much of a PITA for you! I guess I will probably also need the thread pitch, but it's probably standard metric, right?

Mine is ~2013 Veloce 10 Speed

Seems that it might be a proprietary part. If anyone has a bashed up old 10-spd Veloce derailleur they can sell that I can salvage the screw off it would be appreciated!

I have a screw if you still need it.