Happy Christmas Alan,
that very attractive looking catcher design came in wide or regular width to fit either a Victa 500/Supreme Twin or early 80s Mustang/Powerplus respectively. The latter will also go on 1970s thumb latch catcher models that share the VC Mustang chassis such as the Impala, VC Sports, VC 125 Mk III and of course the Mustang of the late 1970s.
Judging by the condition and black colour, that is most likely a replacement catcher which come black as standard instead of the original array of colours they came in.
