Advert for Saving Planet Earth DVD Boxset.

As one of the key issues is an overcrowded planet we filmed the opening in London. Cameraman Gavin Thurston gets shots of people near the Tate Modern.

David in a moment of thought while filming on the London Eye.

It has been calculated that if everybody in the world lived as we do in the UK, we would need three Earths to survive.

Photo by Graham Ross

David does a piece about the extinction of the wolf from the UK.

Wolves survived in Scotland until the late 1600s but were eradicated as an increasing human population cleared the Caledonian forest.

Photo by Lea Aldridge