You need to go back in time. Seriously, there was a member of cnczone using the name Imancarrot who specialised in diamond turning for IR lenses, and other optics. He is/was located in Manchester. Here is his members page. You could maybe scan through his threads and see if he ever gives any non-cnczone contact info.
http://www.cnczone.com/forums/members/imancarrot.html
Maybe a faint hope but nothing ventured nothing gained.
An open mind is a virtue...so long as all the common sense has not leaked out.