Sorry I don't know it but I do know the one you mean.

Is it Black Prince?

Thanks Darren, I’ll Google that . . .

Well, it’s listed as having “bronze” foliage, so I don’t think it can be that one.

Sheilabub Have a look at this link.
https://www.thompson-morgan.com/p/antirrhinum-majus-bronze-dragon/4348TM
Just in case you cannot find the link, here is a copy of their description of it.
"These eye-catching, bushy, dwarf plants have the darkest, almost black foliage we have ever seen on an Antirrhinum! Bred by Thompson & Morgan, Bronze Dragon looks almost as attractive before flowering as it does when smothered in its gorgeous, purple and white bicoloured"

Wow Scotsgran -thank you. The foliage certainly looks very dark and shiny, so I think you have found the one I was looking for. I'm most grateful!

I love all these dark leaves and stems and the flowers sound lovely. They do make a great contrast to all the greenery. I think it is only half hardy but it will probably self seed to ensure its survival.