Hi Brian
Sadly they may have standardised NOW but the ones in this one are 1" long, 26 tpi and almost a square form thread (?) with a large degree of taker under the head for the first 1/4". The diameter ( to top of thread) is 302 thou.
BSF perhaps?
I should add they were certainly put in never to be removed without considerable effort ! Mine have now been extracted, copper slipped and reinserted.
Until I extracted them and compared to the ones shown as a spare available now, I was going to bite the bullet and order a set of jaws etc ( £50 !!!) but they're totally different.
I have e mailed record to see what their view is and will update this when I know.
Made me feel a bit better when I saw the same vice on ebay for £170! Mind you you have to go and collect it. Just about gave me a hernia when I picked mine up !
Thanks one and all
Ian