1942 was a pretty rough year for the Brits. They were doing everything they could to speed production of the new rifles.
First thing that happened was that the Cutoff of the Test rifles was trashed: cut machining time and expense.
Next to go was the Mark 1 rear sight; it was the single biggest bottleneck in production. That super-fine thread was very difficult and very slow to make.
So the Mark 2 double battle-sight (which you have) was born. It is factory-set for 300 and 600 yards, but there is a Table which shows you how to use the same sight at other ranges, although with the wartime SPIKE bayonets.
Later came the Mark 3 and Mark 4 sights and the Canadian variants, all formed sheet-metal (stampings).
Rifles which went through post-War refits generally had the Mark 2 sights removed and the rifles upgraded with the Mark 1 or the Mark 4. Find a 1942 rifle with a pristine Mark 1 sight and chances are that you are looking at a post-war rework. Yours appears untouched, from what I can see.
Trade-Ex has some of the SPIKE bayonets, run about $7, but I don't know about Scabbards. Bayonet with scabbard should run perhaps $15. The VERY early bayonets made by Singer were cruciform in shape, very scarce, sell for buckets of money and likely are too early for your rifle.
Beautiful toy, though!
Hope this helps.
