Looking at the prop blade and markings it's the post-war the prop blade no.3. of the Dowty Rotol airscrew from 50'. Also I would say it could be of a three-blade prop but not necesseraily of the four-blade one.
The prop blade with the RA numbers can be found on the Percival P.56 Provost ( Percival Provost T.1 ). Certainly it could have been used for the British different planes of a such similar type.