reco-prop in luton were always recommended for this sort of work years ago, try giving them a shout!

http://www.reco-prop.com/drive.htm

edited to say that the company seems to have been dissolved in 2016. google links a different website to their company now though:

http://baileymorris.co.uk/

seems that they mostly do props, but may be able to help you out with driveshafts possibly?