Wel Nigel, to comment on your Deumer comment ....

.
Deumer wartime EK1 :
* Unmarked - not sure (?)
* Marked with 3 ( in square box )
* Marked L/11 ( in square box )
* Marked L/11 ( without square box )
* Any others ... ???
Deumer wartime EK2 :
* Unmarked - not sure (?)
* Marked with 3 on the ring
* Marked with L/11 on the ring
As to what timeframe what marks were applied to which crosses, I have no knowledge.
It might " technically " be possible to find an 1957 EK1 marked 3 or 1957 EK2 marked L/11 but I havent seen one yet.
And BTW ... love that vaulted EK1 - gives a more worn and personal look.