On top of the roof of the building in the centre. They're white with a gold finial on the top and clearly visible as you approach the roundabout from Kingston road (A240).
Anyone suggest what these four masts are? - spamcan61
I was going to say that would be a rubbish place for a mobile phone site, with that huge tower block just down the road. but sitefinder shows 3 and O2 sites at that location so looks like they are mobile phone masts.