The few Britishicon navy clasp knives I've seen were dated early fifties. Like the first two photos but with scales, I can't remember the material. That one is missing the scales on both sides. Very robust and useful clasp knife. if a bit large and heavy.

An old sailor told me: in use, open blade and marlin spike, hold in hand with blade ready to cut, spike sticking out the bottom of the hand; good for close in fighting as the spike is under your hand for stabbing and the blade in front for cutting. He wouldn't tell me how he knew this.

The swiss knife is wimpy in for serious work compared to the clasp knife.