I haven't been able to verify the last one so it might be a fake.

You can see all the places in documents etc., where the name "Herbert L. Webster" is mentioned by entering the following in a Google search. site:https://457thbombgroupassoc.org "Herbert L. Webster" <ENTER>   Tip in the future for anyone:    A site: query is a search operator that allows you to request search results from the particular domain, URL, or URL prefix specified in the operator. For example in the above query I'm trying to find anywhere on that website where the name Herbert L. Webster is mentioned.  Making sure to use the quote marks around the name in this case. It's a time efficient way of searching a whole website for a particular word/s, name/s, etc. without trying to look all over the website for what you're looking for.

I tend to lean similarly to your view. I’ve always been under the impression that P1’s and P2’s were being manufactured at the same time or at least in a relatively close proximity. I have seen P1’s early war, I think there’s a picture out there of some on Gloucester and Tarawa. But I have always thought the same about the P2 that it was earlier and produced either before of at the same time as the P1. You do see the green trimming more often on P1’s which is also seen in P2’s. To bad there’s not much manufacture info out there on them and virtually no dates because of terrible depot stamping.

Video of the memorials to the service of the 457th Bombardment Group (Heavy) at Glatton airfield, Station 130. It includes the memorials at three sites.   https://americanarchive.iwm.org.uk/archive/media/httpsyoutubevgu2i0ufiy4

I took your advice and put it next to one of my cannions😆

New to me. Don’t think this is Navy. Maybe Train Porter or some other civilian thing?

Compare the fabric used on D rings and early ‘Pattern 2’ canteens. Note the orange trim on both the left D ring and the bottom canteen. Have yet to see an Orange trim P1 (Canteen photos are not mine) 

My depot ‘M buckle’ pack compared to your P1. Notice how both utilize the same green binding.

Just to add onto @Alwayslookingfordqp   I largely agree with you that the ‘P2’ variant that we have have conveniently labeled as a Pattern 2 is in fact the first Pattern of canteens issued to Marines at the onset of the war. Ill insert a photo of one being used on the ‘Canal’   Most P1’s have green trimming around the snaps, which matches later variants of depot made equipment such as P4 canteens. And the binding on Depot 1st pattern ‘M’ buckle packs.   However if you look at an early D ring pack none of them have this green trimming around the front of the pack. And in fact a lot of Pattern 2 canteens even have Orange trim variants that some D rings have as well. Pretty sure there was just a shortage of Lift-Dots and Depot started manufacturing canteens with snaps instead. Funny that P42’s use the same snaps. Guarantee those came about the same time as the ‘P1’