In the politics of the United Kingdom, the Maastricht Rebels were Members of Parliament (MPs) of the then governing Conservative Party who refused to support the government of John Major in a House of Commons vote to secure ratification by the United Kingdom of the Maastricht treaty (Treaty on European Union). This was particularly devastating, as there were 22 rebels as of the second reading of the European Communities (Amendment) Bill in May 1992, and the government's majority was only 18. The rebels were more numerous than the government's notional majority, so that the Major government was a de facto minority government. The rebellion was largely orchestrated by former Prime Minister Lady Thatcher and Lord Tebbit. Thatcher declared that she "could never have signed that Treaty".

At the height of the rebellion was the 1993 Christchurch by-election, where a Conservative majority of 23,000 was turned into a Liberal Democrat majority of 16,000. The Conservatives fell to a mere 23 points in the opinion polls. John Major threatened the rebels with a general election, which would have meant annihilation for the Conservative Party.

It was an enormously tense time. The Labour Party was bringing heart attack victims and MPs who had just had brain surgery (the "stretcher vote") in to vote in an effort to bring the government down. The loyalists and rebels in the Conservative party also brought in their own stretcher vote, for example Bill Cash organised for one MP (Bill Walker) who was seriously ill to fly from Scotland secretly, then hid him at the rebels' headquarters in Great College Street, before, with Labour connivance, hiding him in the family room of the Commons so that the Conservative Whips wouldn't know; the government consequently lost a vote. On 22 July 1993, on a Labour amendment to postpone incorporation of the Treaty until the Government adopted the 27th Amendment thereto (the Protocol on Social Policy or "Social Chapter"), the government tied 317-317 against the combined forces of some of the rebels, the Labour Party, the Liberal Democrats and others. It was thus only by the Speaker's casting vote that the Government won (the Speaker casting her vote in accordance with the 1867 decision of Mr Speaker Denison not to create a majority where none exists), to date the most recent occasion on which such a vote has been called for. The remaining rebels (who had abstained on the amendment) then joined their colleagues to defeat the main take-note motion 324-316 in dramatic Commons scenes late on a Thursday evening. On the following day it emerged, on inspection of the Division List, that the Government Whip and teller of the Opposition votes Irvine Patnick had failed to notice an overcount of one vote for the Labour amendment. Had he done so it would have meant a clear win without reliance being placed on the Speaker. On the next day (the Friday) the government tabled a differently worded motion to its predecessor, seeking the "confidence" of the House in their policy on the Social Chapter instead of merely "taking note" thereof. As a result the Government easily won the substantive question by 339-299. Had the government lost this motion of confidence, a dissolution would have been requested and might well have been granted.

Bill Cash was absolutely fundamental to the rebellion, organising the finance and offices to set up the European Foundation and to fund legal challenges to the government. Opposition to Maastricht led to the foundation of the Anti-Federalist League which ultimately led to the creation of the United Kingdom Independence Party (UKIP). Certain rebels later went on to join the United Kingdom Independence Party, such as Christopher Gill and Richard Body, with Roger Knapman serving as their leader between 2002 and 2006.

The Maastricht rebels continued to harass the government on European issues, coming within a whisker of bringing John Major down three times. They repeatedly called Major's bluff on an early dissolution of Parliament. On November 23 1994, Nick Budgen asked him whether he had spoken to the Queen about dissolving Parliament. On November 25 1994, Christopher Gill stated that he would sooner resign as a Conservative than vote for the Bill. All those Conservatives who rebelled over the EC Finance Bill on November 28 1994 had the Conservative whip withdrawn. Deselection was threatened (so they wouldn't be able to stand at the next election), and Conservative Whips spat at them. They were constantly harassed by the party. Nick Budgen summed the attitude of the rebels up with this quote: "It would be my general feeling that the transference of power to Europe was so important a matter as to require a vote against any organisation and any party that wished to transfer that power." In 1995 Major called an early leadership election, to attempt to re-impose his authority on the party, and won. However, the infighting did not stop, and the Conservatives were heavily defeated in the general election of May 1997.

Leading rebels

Those who had the whip withdrawn included:

• Richard Body
• Nicholas Budgen
• Tony Marlow
• John Wilkinson
• Richard Shepherd
• Teresa Gorman
• Christopher Gill
• Teddy Taylor
• Rupert Allason

Other rebels were:

• Bill Cash
• Nicholas Winterton
• Iain Duncan Smith
• James Cran
• Michael Lord
• John Biffen
• Michael Spicer
• Rhodes Boyson
• George Gardiner
• Roger Knapman
• Liam Fox only signed 1st Early Day Motion against Maastricht
• Alan Duncan only signed 1st Early Day Motion against Maastricht
• David Willetts only signed 1st Early Day Motion against Maastricht