Photographed at the University of Liverpool Botanic Gardens last
Thurdays. I think it's one of the snake-barks, and lean towards Acer
capillipes.

http://www.stewart.hinsley.me.uk/Images/Acer241.jpg (tree)
http://www.stewart.hinsley.me.uk/Images/Acer242.jpg (raceme)
http://www.stewart.hinsley.me.uk/Images/Acer243.jpg (foliage and
flowers)

(I've compressed the images, but they're still fairly large.)
--
Stewart Robert Hinsley