This is identical to a Barnes frame I’ve owned in the past (now a wall hanging in Blakey’s shed). If anyone ends up with it make sure you run a long enough seat post to get past the top tube, the one I had had had a short post run in it which had turned the seat tube extension into a lever which cracked the seat and top tube where the seat stay re enforcements are.
Vintage Road Bike Frame Reynolds Maybe Triple Triangle Frame Shimano Fixie in St Kilda, VIC | eBay