Wandering around our garden last night, came across this little spider on the Hydrangea. Seems it is a Misumena vatia or crab spider. They are apparently common in southern England in summer, usually found on yellow or white flowers and can change their body colour to match their background.
Not having seen one before we consulted the Internet where www.uksafari.com/crabspider.htm
points out that you can sometimes see two faint lines on their abdomen which are apparent here.
They sit on flowers waiting for insects to land close by so that they can pounce on them and trap them with their crab like front legs so guess this one is conforming apart from its choice of flower!