Easy swap to an existing socket, but could be better
If you are looking for a simple plug-in replacement for Hornby 4-pin decoder this seems to be the only game in town and is simple enough to install into the socket.
Unfortunately the range of CVs is limited and one that I requently adjust (CV5 for maximum voltage) is not supported. With hindsight I would probably have been better off cutting off the Hornby 4 pin socket and hard wiring in a micro decoder from another manufacturer which would probably be more versatile.
It is what it is...