Here's a No1Mk3 I've never seen before

[Thunderbox]

I think there are references to the Indonesians themselves carrying out a big FTR of Enfields and other rifles.

BSA would still have been carrying out private SMLE refurb contracts in 1955, so thats a likely source of a new knox-less barrel. From the photo, the finish actually is reminiscent of Lithgow production - again the timescale and geographical proximity would fit.