Why do political debates often lead to Hitler?
Media playback is unsupported on your device
Video

Why Livingstone, Johnson and Ashdown talk of Hitler

Green co-leader Jonathan Bartley and Breitbart commentator James Delingpole looked at Nazi references in UK politics today.

The pair debated with Daily Politics presenter Jo Coburn, who explained Godwin's Law, after Boris Johnson, Ken Livingstone and Paddy Ashdown invoked war-time references.

Go to next video: Johnson makes EU and Hitler comparison