John Cutler
It occurs to me that not many members have access to Iain Rice’s Cameo Layouts book or have seen/noticed these couplings on Hepton Wharf. I cannot reproduce Ian’s drawings due to copyright but here is an explanatory diagram (I am afraid it is not up to Ian’s draughtsmanship standards).
I actually tested a variation on this coupling using Vincent de Bode’s ideas. Unfortunately I dismantled the test couplings from their host wagons and loco before realising that photos might have been useful. Sorry about that.
Anyway here is a comparison diagram of the variation.
I hope this might help anyone looking to experiment.