42 RM 3RD Pattern knife

[geordie lad]

Hi All
A recent purchase, stamped on the cross guard, 42 RM , also the soldiers name on the sheath, Steel 42 commando.
Anyone know of a period?? the knife has been in a private collection for 30 plus years, no maker marks or stamps.
thanks
Brian

[Infanteer]

Certainly a post war knife. As for the added markings... I'm a bit suspicious but that's because I haven't seen any legitimate unit marked F/S knives before.