The British have always liked marlin spikes on their military knives, and since the Boy Scouts never adopted an official pattern here, it may have been the cutlery firms themselves that produced one, already having the tooling, and the skills to make them. The most common term for this type of knife here was, and remains, 'clasp knife', even though they are not actually a clasp knife. Boy Scout Knife (Centre), with a British Army WW1 pattern (L), and a British Army WW2 pattern (R)
That's a particularly nice example of the 'Scout Knives' we all carried as kids. Known as 'Whittle-Tang Bowies' in the trade, the Sheffield firms must have produced millions of them over the years. Here's a Maleham & Yeoman 'Scouts Woodcraft Knife' I gifted to John Maleham, of A. Wright & Son, a few years back.