Definately not Gunnera, the leaves are not big enough, I don't think Gunnera flowers either.
Not a castor oil (Fatsia Japonica) as they are evergreen, had a couple at the last house.
This plant is not evergreen, it's starting to die off. At first I thought it was two separate plants but looking closely saw that the flower stem was connected to the leaves. It's almost like a mutant Hollyhocks, but with wrong leaves and not quite right flowers.
I'll take the photo next time I go to the garden centre and see if they know. Never seen anything like it before. There's one in the front garden too.