Honestly Chris, I do not think I ever saw it in the flesh on another Mk1 800 that wasn't the one I owned, it was bloody rare, probably because it looked pants in the colour chart in the brochure, and dealers never carried any stock that showed prospective buyers the colour for real.
Even when I bought my one, it was with a heavy heart, there was a zinging BRG car there at the same time with lower miles too... but it was a saloon and I really wanted a fastback.
By the time I was about 1/2 way back to destination after picking it up (London to Preston), seeing the reflection of street lamps in the bonnet, and getting the mirror image of it in service station windows as I progressed north, I began to understand what a great colour it was. But you're right, very easy to believe/think it was never on a Mk1 - I probably would have thought the same had I not owned one
God I wish I'd' kept it!