I have never handled a Milbro G55 and could be completely wrong, but I don’t believe it shares much in common with the German-built model 50. It is a smaller gun which, I suspect, may have been based on the pre-war Diana model 30, which was a military trainer designed for young shooters, and I believe, the only pre-war Diana underlever with a full-length stock.

Remember that Milbro’s post-war Diana-branded guns were derived from pre-war German machinery they purchased after the war. I’ve often wondered if the G55 shared some internal parts with the Milbro model 27 (as did many other Milbro models).

The model 50 was a clean-sheet-of-paper post-war design, with the then-new ball-sear trigger, and which shared parts with the barrel-cocking model 35.

Again, basing this on my reference books rather than an actual example! I’d love to learn more about the G55.