This is Sinningia tubiflora, a plant long known and grown as Achimenes tubiflora . I learned its name as Achimines tubiflora, and since I don't travel in gesneriad circles I was not aware of the name change until very recently. But I never forgot the plant because the descriptions I read contained the magic word "fragrance".
Fragrance is not the only temptation it offers; it's apparently almost hardy. I wintered the plant above in a cold frame, and that's where it will spend the upcoming winter.