Hi pendragon, sorry - just logged in and seen your posts. Nice conversation you've been having with yourself. Anyway, well done for finishing without any feedback :-)
I thought just over 500 metres was something like "501 metres" or "DIM" (Roman). Anyway, it is indeed L*. There aren't many two letter words starting with L, so you should get there.
Thanx IXION for the wordplay at 10A. I got there by myself once I decided that "position" was not necessarily the definition.
I have finished the grid, but I can't justify the first three letters of my answer to 7D. I'm assuming they match with "nuts", but can't see it. Acronym?
That was other one I couldn't work out...assuming last 3 are new soldier gets rejected, the best I can come up with is...
ens(existence)=is, with nuts indicating unorthodox usage - not at all convinced though.