PTS is PTS isn't it? My current employer do all the PTS stuff internally, you still get a Sentinel card.
No, PTS isn’t transferable between TOCs/FOCs unless it’s done externally I believe (Or by obtaining a Sentinal card?...you have one of these and it’s internal so maybe it varies?). I have PTS through my TOC, but if I was to leave and join another company (fingers crossed), I’d have to redo it as it was done internally through our operations trainers (I don’t have a sentinal card).
I think the idea of Sentinal is that the holder could be working on any track and need a transferable system, whereas I’d only be working on certain infrastructure? Hence why it’s mostly engineering companies who use Sentinal. Also, my PTS was (until very recently) only valid on DC lines. Now there’s an audition for AC too due to a lot of areas having overhead power these days.
The medical however that one takes when joining a TOC or a FOC for any safety critical role should cover you for your PTS as well. Can’t think why it wouldn’t?