On November 22, 1990, Margaret Thatcher, the longest-serving Prime Minister of the 20th Century, announced her resignation from the office after 11 and a half years.

The Conservative leader chose to stand down after her Cabinet refused to commit their support to her ahead of a second round of leadership elections.

Growing party opposition to her stance over Britain’s involvement in Europe, a 14-point deficit to Labour in opinion polls, and the resignation of Deputy Prime Minister Geoffrey Howe had left her position in jeopardy.

She was challenged for the leadership by her former Defence Secretary Michael Heseltine; despite being defeated in the first ballot, Heseltine won enough support to force a second vote.

Initially Mrs Thatcher said she would “fight on and fight to win”, but consultation with her Cabinet persuaded her to withdraw.  Her Chancellor John Major and Foreign Secretary Douglas Hurd would go on to face Michael Heseltine in the second ballot, Major eventually winning the contest.

[Read more: May 19, 2004 - Dads' group hits Tony Blair with purple flour during Prime Minister's Questions]

After meeting the Queen and making one final Commons speech, Mrs Thatcher left office, saying "We're happy to leave the UK in a very much better state than when we came here”.

Also on this day: November 22, 1963 - US President John F. Kennedy assassinated in Dallas