Margaret Thatcher was proud of her scientific training. It was one of the reasons she was suspicious of grand economic or sociological theories: she did not see them as truly scientific.

She was not averse to outflanking someone who knew little science with some deftly deployed chemistry. I saw her do it to Helmut Kohl, whose advisers I had stoked up to press her on acid rain, when I was as a minister trying to change British policy and get expensive flue gas desulphurisation equipment added to our coal-fired power stations.

She obviously saw me coming a long way in advance. We arrived in Bonn on hot midsummer day of smog. "Now Helmut," she said to the cowering Chancellor, "I will tell you what you have here. You have got an inversion and a smog. If you had proper clean air laws here like we have you wouldn't have this trouble. Let me explain the chemistry . . ." We heard no more about acid rain on that visit.

She was unmoved, as always, by clamour from pressure groups - on that issue as on any other. But on another, arguably more crucial, environmental issue, the damage to the ozone layer done by CFCs, where there were powerful industrial lobbies opposed to action, she moved quickly, putting Britain in the lead among the countries who generated effective, legally backed international action. She studied the science closely, and understood it. Perhaps it helped that key work on measuring the damage to the ozone layer had been done by the British Antarctic Survey.

David Fuller's view This is a knowledgeable and fitting tribute to the late great Margaret Thatcher.