The benefits of insomnia...
The rifle is marked on the buttsocket...
The magazine bottom...
...and the bolt handle.
The rifle is in standard No4 configuration, though the receiver is an erased Fazakerley No5 Mk1.
The "F" marked trigger/sear assembly is why I say this otherwise blank receiver is FAZ.The bolt is an "F/54" replacement part and the barrel is an "M47 C 1953" replacement barrel.
There is a "Crowned BM" proof on the receiver ring, but as this is not repeated on the barrel and bolt, I suspect the rifle was assembled in the Orient from salvage and spares.
-----krinko