It does not matter which hitch coupling is used, it is the chassis make that determines which handbrake bits are used.
Yours looks like BPW lever on a BPW chassis, which Elddis used for quite some time.
Is it that the piston on the damper has snapped? In which case would it be possible to get a local garage or the like to weld the break? The damper does appear to pivot on the rivets top and bottom which will need greasing before refitting. Just an idea if you are struggling to find a replacement. Other than that you could try a caravan breakers.