The RAF stamp or engraving was given for the ones re issued for ww2. There's another engraving on the left side of the gun for the ones issued in ww1. I can't remember off the top of my head but I believe it was an engraved arrow. This particular gun was passed down from a Canadian pilot who was stationed in Europe in ww2 and brought back with him, and has made it into my collection.
In my readings, the enfield refinished models have an engraved "E" as well stamped on the frame. I have not seen this mark.
There aren't too many that weren't converted to .45 back in the day, I also have the proper mag for it, unforunetely the serial doesn't match. The mag serial looks like it was hand engraved, not done by a machine.
Another neat fact about it is the serial # being that it's one of the first ; 6 hundred made in the series. Crazy that it's almost 100 years old.
Hi,
Sorry for the delay in this reply, I've been too busy to sit at my computer the past few days. I see you have now listed the pistol on the EE. I think you need to double-check your resources, as there's many errors in your information.
Your pistol was part of Contract No. U.S. 6755-MM264, placed May 7, 1918. This contract was for 10,000 additional RAF pistols at the rate of 600 per month, with 30,000 extra magazines.
Your pistol number W106261 was shipped Mar. 20, 1919 several months after WWI ended. It was near the end of the contract and thousands of pistols are in the 'series' prior to it.
It has the following standard markings from that shipment:
RAF: Hand stamped by armorers, signifying Royal Air Force. Pistols serialed above W100000 without the RAF mark may have been sold to individual officers or issued to other military organizations.
Broad arrow: The standard British government property mark.
Crossed pennant: British military proof mark stamped at Colt.
G2A Inspector mark: Inspected and proofed at Colt by British inspector G.W.R. Stedman.
The pistol also has the following non-standard markings applied since leaving the factory:
Magazine serial number: 1911 magazines were never factory numbered to the guns. Whatever serial number is on the magazine was applied by someone after it left the factory. It could be an old RAF rack number, some units liked to apply such things and I have seen them before. Not too often found on magazines. I wouldn't be surprised if the magazine also had a broad arrow applied.
British commercial proofs on the barrel: From your EE ad, the barrel on your pistols shows British commercial proofs that began being applied in 1955. As such, the pistol did not leave the U.K. prior to 1955.

**Besides the obvious post-1955 export proofs, it would be highly unlikely that a Canadian pilot would have carried a pistol chambered in .455 auto during WWII. That ammunition would have been extremely difficult to find. A few Canadian pilots are known to have carried 1911's chambered in the more common .45 acp during that time.
The finish on your gun is not original and while it's hard to say from the photos, it's probably an arsenal re-finish. Many of the RAF pistols sold as surplus and brought to Canada at the same time as yours had that finish. It appears however that this pistol did not receive the Enfield inspectors mark at time of refinish - I have observed others like it. It is also possible it was parkerized commercially by a previous owner.
While your pistol is not what you describe, it's still an interesting gun from the inter-war period that served with RAF during that time.
For additional research, the best book for British 1911's is Charles Clawson's 'Colt .45 Service Pistols' also know by collectors as the 'big book'. This is an expensive book and sadly out of print, but nobody else has accurately covered the British contract 1911's to same degree of detail.
Regards,
-Steve