Desperate times: Enfield No1 MK VI

-I've had Enfields back on my mind the last 3-4 months as I chased some rare .22 trainers: a No7 and a No9. Wasn't able to get either but then someone's Enfield collection came to auction and in a large batch of very nice items was something very much of interest to me.
-This is an Enfield No1 MK VI Trials Rifle. Or more specifically, it's what's left of a No1 MK VI after a WW2 rework. I won't bore you with details of the No1 MK VI history as Ian @ Forgotten Weapons has a nice video about the short history of this trials rifle.
-What I'm going to focus on is what happened after trials completed. Approx. 1500 rifles were built and fielded in the early 30s. Afterwards it was decided to adopt some additional changes to strengthen the action (look at the left side of the receiver to see what I mean) and improve the rear sight. These were instituted in the first prototypes of what became the standard No4 MKI. So with the No1 MK VI now a non-standard pattern they were placed into storage.
-Fast forward to The Battle of France and the evacuation @ Dunkirk. Massive amounts of material was lost and anything that could be safely fielded was taken out of storage and placed into service. This included the No1 MK VIs. Many were reworked into sniper rifles. Over time many of these rifles found their way back to arsenals for repair/rework. This example was one of them and it was rebuilt to get it as close to current No4 pattern as possible. In this case it got new No4 furniture, front band, rear sight, front sight guard and the cut-off was removed. The original butt socket markings were removed and a new SN with "A" suffix was stamped to denote that it didn't have std pattern parts.
-Original configuration No1 MK VI examples are extremely rare and stupid expensive as Enfields go. Figure on paying over $10K for one. I took some photos of a South African Savage No4 MKI* so you can see the difference in the receiver. I also grabbed a photo of an example in original configuration (very cool IMHO). BTW, found a period brass oiler in the buttstock, a nice bonus along with the period sling.

An original configuration No1 MK VI. Note the checkered forestock, waisted front sight guard, "button" style early cocking knob. On the opposite side you'd see a brass ID disc in the buttstock along with the cutoff.

In the pictures of the paired rifles you can see how the receiver sidewall thumb-slot radius was reduced to strengthen the action body on the no4's. and then carried right up to the top of the receiver ring. Thats the only thing I can recognize off the top of my head with the trials rifles. Also I think the induction hardening was further improved in the locking recesses and metallurgy to the bolt body and strength-ed behind the long lug on the right. Changes obviously made to the bayonet reinforce with the clam-shell halves. The waisted foresight protector I would like to find one day. I also seem to think there was two different types.
The rifle in the last picture also has a stacking swivel which you do not see very often.

Cut off's milled and then stamped and Mk1 hinged bands are some other traits as well as butt socket with GRX an linished serials just like you said. Magazine box is interesting too because it's like half no4 and No1 with the rear reinforce nearly to the bottom of the box but with the front stopping short like a NO4. The checkering is over the top in the last picture but I don't understand the rigging for the sling. Probably doesn't get used much more anyhow. The pictures show a great comparison thanks for posting them up.