Cosmos bipinnatus, 'Sonata' Series, 'Sonata Carmine' is the best fit Janet, apart from the too large heart and the shorter petals, the photo of it in the chilternseeds site also show the slightly fluted petals..
It could be the growing condition or that it had been forced to bloom by the nursery that made mine look a bit odd.., if it had lived longer it might have shown its true shape..
