I looked at about 500 Alvis with Graber body photos and never found this car complete on the net.
However, I did see a photo of a TC08G prototype of the TD21 with bodywork by Graber done in 1956.
It had the same "driving lights" configuration and the same location of the turn signals. The photo was of just the body shell of the car
which was under restoration but not completed when offered for sale in the UK I believe.
This might be your puzzle car.