Trains leave southwards from Streatham to enter the loop and then return going northwards.

The short section between West Sutton station and West junction is known as the "Wall of Death",[3] possibly due to the very steep concrete walls to the cutting on both sides and the sharpness of the curve which resemble the motorcycle ride at a funfair.

In a clockwise direction round the loop, the stations are: Traction current is supplied at 750 volts DC via the third rail.

[4] Thameslink runs services from St Albans, via Blackfriars round the loop.

Recent proposals were to increase the frequency of the Thameslink service by terminating at Blackfriars.