KEF, hi - when I grew it is was called gunnera magelenica (Hmm, not dreadfully certain of the spelling there!), at one time Beth Chatto's nursery stocked it, but no idea if they still do. Try the plant finder on the RHS website - they will be likely to know if it is available. There are in fact two, but I cannot recall the second ones name. It is some years since I grew them, but they were a delight. I'll have a look it my records and see if I can find more details, but I promise nothing!!