L.gary, it must have been post '61. The Concorde project didn't start until 1962. The flight of the first prototype was '69.
G-BBDG used to be at Filton. She was the last pre-production prototype and was almost to production standard. She even flew in BA colours but only for test - never in service. She was a spares source for the BA fleet and at end of Conc ops in 2003 was little more than a shell.
As stated above, at end of Conc ops she was shipped to Brooklands where, using the much of the interior from G-BOAB at Heathrow, she was restored for public tours.