So I've just seen this unit in Reading but it wasn't in the pink livery - reverted back to old Railtrack livery. Guessing the pink was a vinyl that has now been removed? Definitely 98926/76. Perhaps old news?!
A post on social media by SES yesterday mentions that this has been adapted to carry a couple of Load Tray trailers, one on the roof, the second on the rear. What may be a first however, is that to avoid manual handling it is accompanied by a portable hydraulic lift to raise or lower the trailers.
For the record, a Youtube video shows this machine has recently been carrying SES branding, whilst retaining it's TRS fleetnumber, being used on a flood alleviation/drainage project at Fulwell undertaken by SES. I am advised it was back in TRS branding as of yesterday however.
Jim, I apologise if I have misunderstood your earlier comment, but my immediate thought is that this may be a second hand "base" machine which has been converted for rail use after an earlier career in civils work. The build number would also support this, commencing "069XX" whereas other recently delivered machines seem to commence "075XX".
Whilst this wouldn't be the first such example, a number of L & W Contractors PW160s having been sourced secondhand (quite a number from HE Services) prior to conversion by Rexquote, it's a little surprising as I had believed most Liebherr models were purpose built for rail, rather than converted. I stand to be corrected on this however.