"Quite why the designers didn't go for the Browning 0.5-inch,even when the Belgians were using them in their Hurricanes,is beyond me".
Good point. And quite why the UK never went for his designs until long after he died (1926 I think) is one of life's enduring mysteries. Even then, it was almost by default due to his long association with Fabrique Nationale des Armes de Guerre (have I got that right?). Having said that, most 20th century small arms work on his principle of delayed blowback. Everything else is cosmetics/ergonomics. I read once that the US Army trials plan for their "LMG" in the early 1900s called for a 10,000 round demo and they would assess stoppages. Browning himself spent a day firing over 20,000 rounds from one BAR, then in darkness field-stripped it, cleaned it, assembled it and carried on firing. No stoppages. (A hundred years later, can the SA80/LSW do that?). The Bren was good (30 years later), but the first thing you had to master was the Immediate Action due to continuous stoppages. (Gun stops, cock gun, mag off etc). The only criticism of any of his designs was the "Hi-Power 9mm" (around 1924 when he was getting on a bit) and still in service in the UK. The double action was and still is "an ingenious solution to a non-existent problem". But he was an engineer, not a soldier. And a very fine one.