Wasn't the prototype made at Crewe? Was it in 1972?
May have been built in Crewe (power cars) and Derby and may have been built in 1972 this photo is not Crewe
I'm going to take a punt at the location.
Bristol Bath Road?
Not Bath Rd either
This photo taken in 1975 at Swindon Works Open Day in 'A' Shop Swindon, the power car in the shot is 252001 and it was the whole train in the shop (one of the power cars 252002 might have been outside at the western end) on a road just inside the shop at the South end (Main Line end) it sat across both the traversers in the shop.
Swindon Works did manufacture components and sub assemblies for the
HST▸ 's, the 'A' Shop now sadly demolished it was huge