Margaret Thatcher was a strong supporter of the single market in Europe and signed the Single European Act.

BBC: Europe and Baroness Thatcher: The great divide

Mrs Thatcher came to believe that she had been tricked into accepting the Single European Act in 1987.

ECONOMIST: Britain and Europe

In 1987, 70% voted for the Single European Act.

ECONOMIST: Ireland

She remained the rallying point for the Eurosceptics in the party, who conveniently forgot that it was their heroine who had signed the Single European Act, introducing majority voting and conceding new powers for the European Court of Justice.

ECONOMIST: John Major

It was Margaret Thatcher's government, a Conservative government, that introduced the Single European Act that allowed British businesses here in Birmingham, in the Midlands, to invent things, manufacture things and then export them completely freely into the largest consumer market in the world.

BBC: Transcript of Nick Clegg interview