Member Defections: Automatic By-elections

Debate between John Lamont and Roz Savage

Monday 16th March 2026 Westminster Hall

[Dr Savage]

The hon. Gentleman makes an excellent and valid point. My main job today, on behalf of the Petitions Committee, is to present both sides of the argument, but the point about data on voting intentions, which we work so hard to glean on doorsteps, is a key factor in the debate.

Others raise concerns that a requirement for a by-election could have unintended consequences, including potentially strengthening the power of party leaderships or discouraging MPs from following their conscience due to legitimate dissent. At this point, I want to clarify that when talking about defections, I am not talking about the case where an MP loses the Whip for reasons to do with the leadership, but about voluntary defections undertaken by an MP themselves. I do not think any of us would want a world where party Whips could threaten an MP with a mandatory by-election if we displease them in some way.

Public opinion on this question appears to be mixed, although polling suggests it is an issue on which many people hold strong views. Some surveys indicate that around 40% of respondents believe that it is unacceptable for an MP to defect, while others suggest that a majority of voters think a defection should trigger some sort of electoral test. Those numbers do not resolve the constitutional question, but they suggest that people far outside Westminster really care about this matter.

It is also worth putting the question into perspective. Party defections in this country are relatively rare, although they obviously sometimes occur in clusters during periods of political turbulence—possibly such as we are going through now. The last MPs to resign their seats and seek fresh mandate after defecting were Douglas Carswell and Mark Reckless in 2014, when they left the Conservative party to join UKIP. They refought their seats in by-elections.

[John Lamont (Berwickshire, Roxburgh and Selkirk) (Con)]

The hon. Lady is making the case well on behalf of the Petitions Committee. Over the years, there have been a number of examples of some of my former Conservative colleagues ending up alongside Lib Dems in the House of Commons. In those circumstances, is the hon. Lady of the view that there should have been a by-election for those MPs to get their mandates restated?

[Dr Savage]

I thank the hon. Gentleman for making that point. What we are talking about is the principle of the matter rather than specific defections from any one party to another.

This constitutional question has also been considered by Parliament previously. In 2011, a private Member’s Bill proposed that MPs who changed their party affiliation would have to face a by-election, and in 2020, another Bill proposed extending the Recall of MPs Act 2015 so that a voluntary change of party could trigger a recall petition. Neither progressed through Parliament, but the fact that the issue has arisen more than once suggests that it raises enduring questions about representation and accountability.

I would like to share some perspectives from other countries, because this is not a uniquely British debate, and other democracies have taken different approaches. Some, such as India, have adopted strict anti-defection laws under which MPs can lose their seat if they leave the party on whose ticket they were elected. Indian MPs are also, for the most part, compelled to vote with the Whip, which must make votes very, very boring. Others, such as New Zealand, have legislation designed to discourage what is sometimes referred to as “waka jumping”—I am reliably informed that that is effectively jumping from one canoe to another, which I can say from personal experience sounds like a very bad idea—although that approach has also prompted debate about the balance of power between MPs and party leadership. South Africa experimented with allowing MPs to cross the Floor, but later decided that that was a poor idea and prohibited it. That shows that views can change about how best to preserve electoral legitimacy.

The UK system has its own traditions and constitutional principles. Party affiliation plays an important role in how Governments are formed and how legislation passes, but MPs are also expected to exercise independent judgment. All of that means that there is no simple or obvious answer to the question raised by the petition of whether the current arrangements already strike the right balance between representation, independence and accountability, or whether there might be merit in exploring alternative mechanisms.

What is clear from the petition is that many members of the public care deeply about the relationship between voters and their representatives, how it works in practice and whether they feel that they are being represented in this place. I very much look forward to hearing the views of Members from across the House.