I saw this on a local fb bike group a minute after it was posted and was off like a rocket.
It's a Grand Sport! Beausaged to hell. 1973 based on the Brooks date code.
I took it home and started breaking it down. The seatpost, surprisingly, came free. So did the pedals and stem, which has no cracks at the square corners of the expansion slot. Red C (for Carlton?) seatpost binder, and the white Carlton hoods are dirty but neither cracked nor sticky. I threw the delrin Simplex shifters and derailleurs away. Not touching the cranks until I have access to my Wera hex wrenches, which I hope will remove the caps without damaging them. Normandy hubs, worn-out 5 speed TDC freewheel, rims in good shape, the Mafac Racer on the back has suffered some inappropriate hardware substitutions. The headset has been replaced at some point with a Hatta Vesta.
The bad:
Both seatstay caps have these edges which are rusted through. My best guess is that they were barely brazed on in the first place. I'll probably clean the rust up and fill the cracks with JB weld.
Also a big ding on the top tube.
This frame is too trashed to flip or restore IMO. I think I'm going to build it up as a singlespeed coaster-brake beater with fattish 700c tires and use it for a loaner; if and when I do I'll post it in the Grand Sport thread. If anyone wants the freewheel, hubs, pedals, Brooks guts, or handlebars, let me know and you can have them for the cost of shipping, or as trade for a set of North Road-ish handlebars.