Hi Louise,
I found out this plant is called Phal. Anthura San Lorenzo. The nursery I got it from must have bought seedlings from Anthura.nl
San Lorenzo is only a growers name. I can call them back after 1 pm to speak with one of the "Phal. men" and he might have more information for me. If anny new information, you'll read that here.
Again I was surprissed with the willingness to help me out!