This picture was taken standing exactly on the Prime meridian of the world, the Airy meridian. The Airy Meridian is shown as a yellow line and just clips the corner of the bungalow on the extreme right of the picture. The meridian monument is on the OSGB36 Bradley meridian 6 metres further west. The Bradley meridian is shown as a green line. Ordnance survey uses the Bradley meridian on its maps and charts.

Many of the pictures in Peacehaven on this site were taken standing on the Bradley line. I originally assumed this monument was on the Airy line, but with a WGS-84 longitude of 0.093 minutes west it is definitely on the Bradley line.