Sacha wrote Dahlia coccinea 'Palmeri':

No, we don't have that but I think that's one she was trying to
describe to us. I'm sure Ray would be very grateful to give a home to a
poor orphaned Dahlia. I think he said he'd had D.merckii and lost it
somehow, so he was rather glad to get it again. There's another
interesting looking plant she's included and I'll get the name tomorrow.

That's decided then. Next time I come over I'll bring it with me. When I find I've got room, I can beg a cutting ;-)