Outer London Defence Ring

It was intended as a defence against a German invasion, and was part of a national network of similar "Stop Lines".

In June 1940, under the direction of General Edmund Ironside, concentric rings of anti-tank defences and pillboxes were constructed in and around London.

[1] The Outer London Ring was the strongest and best developed of these, mainly because it could be constructed in open countryside.

Work on all the lines was halted weeks later by Ironside's successor, General Alan Brooke,[2] who favoured mobile warfare above static defence.

North of London the ring followed a path similar to the route now taken by the M25 motorway, from Watford, following the River Colne, through Potters Bar, Cuffley, Nazeing, then running south through Epping Forest, Loughton and Chigwell.