In my collecting days I had a few of these and looked at probably a couple of hundred over 30 years, never seen one with the added pockets, though I did have a Fleet Air Arm version that had the hood altered to make the collar. I would say a good used wartime one is probably warmer than a B3 as all mine had thicker fleece. Originals Irvin's tend to last better than American sheepskin though I think it is something to do with the outer coating. Not a jacket to get wet though, originals tend to smell like an old wet dog, or should that be sheep till dried out, also quite hard to apply leather preservatives to due to the finish on the jacket or trousers. Thought you may like to see this; the worlds worst original Irvin. Bought from Westcliff on Sea Army and Navy surplus in the early 1960s it remained in the purchasers possession for about 35 years from when he was 14 and a size 36 to when he was aged 50+. Thinking it would be worth a few bob he tried to sell it to me, I only bought it out of sympathy and managed to get it for 2 cans of lager that were on the back seat of my car. Eventually I posted it off to Aero Leather as a swap for some gloves they were selling at the time.
Thinking it would be worth a few bob he tried to sell it to me, I only bought it out of sympathy and managed to get it for 2 cans of lager that were on the back seat of my car. Eventually I posted it off to Aero Leather as a swap for some gloves they were selling at the time.
And here is a better one.

£450 to Norway, size about a modern British 44
Can you date it Andrew? Sorry no back view but it was a main two piece. A couple of on base repairs to armpits but thats about it.
John