I ended up buying a set of these from Shawplan.
They can be made to fit.
DP50-01Buffer beam footsteps for Lima Class 50.B4mm
Hornby do not have spares..which is a shame as two of my four were loose or off when I got the new loco...
Does this help?
https://www.burnhamandhighbridgeweeklynews.co.uk/news/14140234.disused-railway-line-could-be-reopened-as-huntspill-is-set-to-see-enterprise-park-work/
https://en.wikipedia.org/wiki/ROF_Bridgwater
As a wise parent once said to me in the context of coaching a sport.. "just because you're paid doesn't make you professional".
It's excellent Rob btw.
Chris