There are not many medium wave pirates operating in the UK, but one that's been going for many years is Radio Britannia from South Yorkshire, in the north of England. Now the station has been logged in London, 175 miles away, on its frequency of 1476 kHz.
It was heard on a Perseus SDR and flag antenna by the DXing et all blog. To hear a clip go to: http://www.swradiorelay.com/
(Source: Mike Barraclough, We Love the Pirate Stations Facebook group)