The speech was some time around 1988-9, and was written by Sir Crispin Tickell, former UK Ambassador to the UN. Thatcher was trying out the argument that envisages some other threat than the Soviet Union as a motivation for foreign policy. Tickell wrote a book in the early seventies about how pollution demands the invasion of small countries by more enlightened ones, to stamp out pollution. The Conservative Party has always had its social core in the countryside and so subscribes to the old fashioned version of conservationism. There is a good book about the clash between the old conservationism and teh new by Phil McNaghten and Urry, called Contested Natures. -- Jim heartfield