Wrong post code for lat and long

[tommy7600]

Hi,
for http://uk-postcodes.com/latlng/51.35480499267578,-0.4682950079441071.json I get KT130YQ instead of KT13 0SL

[tommy7600]

http://mapit.mysociety.org/nearest/4326/-0.4682950079441071,51.35480499267578 returns correct data