I think it would be highly unlikely that someone would change an Automatic into a Manual Car, because it's not just the Gearbox that changes, it's the Linkages and the Electrics/Electronics that pair it up to the ECU.
So by the time you add in a changed loom, possibly a different ECU Set and a gearbox, and all the Labour involved you could easily have bought another Car (Unless you had a donor vehicle).
You could try a Registration Number/Chassis Number check at a Local Vauxhall Dealership, or even at DVLA easier by telephone if you can actually get through to a real person.
Stew
So by the time you add in a changed loom, possibly a different ECU Set and a gearbox, and all the Labour involved you could easily have bought another Car (Unless you had a donor vehicle).
You could try a Registration Number/Chassis Number check at a Local Vauxhall Dealership, or even at DVLA easier by telephone if you can actually get through to a real person.
Stew