I don't know the details of this particular case, but I wouldn't jump to the conclusion that it is a widespread issue for railway preservation. In most cases I'd expect BR to have done the remedial work before vehicles passed into preservation.
BR was diligent, and the vehicles which had gone for preservation before the sale of asbestos-containing vehicles was prohibited by law were subject to a thorough strip and inspection before they were allowed back on to the network. I doubt that any significantly-contaminated stock went into preservation latterly, and maybe never apart from steam locos with special conditions on the sale.
Regarding these passenger vehicles (if they are the Met Cam pullmans) I know for a fact that
a) Carnforth set up a dedicated asbestos-stripping cell
b) the vehicles were taken apart internally, moved into the cell one at a time and the sprayed internal lagging was very thoroughly removed back to a bare body shell.
c)
when a coach was fully cleaned staff from BR Scientific Services made a detailed visual examination of the interior, scrutinising all crevices where asbestos could have penetrated, and then did a disturbed air test - in which all cleaned surfaces were battered while air samples were being collected. I know because I did them. (This is the same test applied to staffed or public areas of stations or any other premisses which needed to be stripped.) BR testing was feared because it was never paid for by the stripping contractors, only by the clients.
Only after a visual "pass" and then when no asbestos had been found in the air samples would approval be given for the coach to be re-sealed on the inside, rebuilt and allowed out for use on BR.
I don't understand how the electrician acquired the problem, but the trouble is that our generation got exposures all over the place early in our life. I am very aware that I went to a new school in the '60s which had been built with loads of brown asbestos board, travelled on the newly-upgraded WCML which had lots of asbestos-containing materials in its stations, travelled in ships which were spray-lagged and undoubtedly had all sorts of transient exposure in other places I could drag up if I put my mind to it.
Not smoking makes a big difference to the risk, also avoiding gross exposures. At the start of my career I think there were stripping operatives who didn't give a toss about either risk reduction measure...
