the shape of the trigger looks to be rigby,the front sight is not a traditional early rigby ,but is a sight that ive seen on another owned by ken waters in 7x61 ,,styling from the 50s ,,its only lately that gunbuilders have been using the "275 rigby " instead of 7mm so seeing that this gun is obviously at least from the 50s its could be original from rigbys ,,send a pic to paul roberts at jefferies he may be able to help ,,...paul