Hi Dano,
ime sure Darrol has hit on the right answer, maybe some were done for the 'Senior' Instructor whilst the erks had to do with the plain ones.
Certainly mine has no damage whatsoever and dosnt look like its ever been thrown. I have a No 23 ashtray thats also been nickel plated but thats showing a lot of wear, maybe not done to so good a standard as the 36.
Ime also sure a lot were done as momentoes and parting gifts from the Service and turned into cigarette lighters however these in my opinion, for what its worth, were also badly mullered in the process.
However, remember, the plating process cost quite a bit of time and money compared to just painting them white.
Here is a really badly buggered lighter, a Mk 2 Mills thats been ground down all over and been made rather a mess of. I seem to remeber i got it off Paul the Grenade some years ago, came with a lovely Singer base plug.
Andy