Thanks Ben. I spotted some in Inner Temple Garden when I was there for Open Squares weekend and asked the head gardener what it was. Apparently it's Aruncus dioicus: http://apps.rhs.org.uk/plantselector/plant?plantid=180 Shade loving, which is handy as that's where I planted it while trying to ID it!
Can anyone tell me what this shrub is please? The leaves are very similar to raspberry leaves, but it has long catkins/racemes of flowers, a bit like solidago. Many thanks!