Piccadilly Line 90 Years Extension Rail Tour Train At Southgate Station 

The London Underground 1938 tube stock Heritage Train passes through Southgate railway station.
It is travelling from Oakwood to Acton Town as part of celebrations for it being 90 years since the opening of the Piccadilly line route between Finsbury Park and Cockfosters stations.
The southbound platform at this station is the only location on the London Underground where a passenger standing on a deep level tube train platform can peer through a tube train tunnel and see daylight.
(At Kensal Green the station is in open air and Gloucester Road is a subsurface network station)