The final programme in the series brings the relationship up to the present day. It reveals: the full extent of support given secretly to Britain during the Falklands War - 'you would have been defeated without us', claims the Secretary of the US Navy; Mrs Thatcher 's rage over the invasion of Grenada - 'like Krakatoa', reports someone dining with her that night; and the divisions created by the Tripoli raid - 'the Americans pushed us to the edge on that one' says one Cabinet member. The relationship under Thatcher and Reagan has been based on a shared belief in strong defence. But, David Dimbleby asks, what happens next if America thinks the Soviet threat is receding.