Member Defections: Automatic By-elections

Debate between Robbie Moore and Lisa Smart

Monday 16th March 2026 Westminster Hall

[Lisa Smart (Hazel Grove) (LD)]

I am loath to say that I am delighted to have you in the Chair, Sir Roger, because I feel we are all missing out on a good hour’s worth of content with you there rather than here, but it really is a pleasure to serve under you.

Since the 2024 general election, we have seen the start of a slow procession of former Conservative Ministers and Members of Parliament moving to Reform UK. These are people who spent years in government and claimed they were there to make a difference—and they did leave a difference behind them, but that difference was far too many crumbling public services, a cost of living crisis and a legacy of broken promises. Rather than accepting responsibility for their actions, they have crossed the Floor for a new start, making no attempt to rebuild the public trust they broke.

My hon. Friend the Member for South Cotswolds (Dr Savage) alluded to a pattern of very large concentrations of signatures making their way on to this petition—one of politicians prioritising their own political future over the parties their constituents voted for. I understand why some voters feel betrayed and that their MPs are not moving to another party from a principled stance. These MPs clearly feel they are fleeing a sinking ship and are hoping that voters are too distracted to notice. But their constituents have noticed, with almost 130,000 people signing the petition that has resulted in this debate, including more than 200 in my Hazel Grove constituency. I understand people’s frustrations, especially as many of the constituencies that had the highest numbers of signatures were those whose MPs had defected. They feel, rightly, that something has been taken from them. For that reason, some feel betrayed.

Most voters will not have read the full manifestos of all the candidates standing for election, but I can see why people would be unhappy, particularly when their MP joins a party that does not align with their views and values or whom they thought they had voted for. We are talking about a party whose former Welsh leader was imprisoned for a bribery conviction related to Russian connections, a party filled with swivel-eyed Trump supporters, a party that platformed a vaccine conspiracy theorist at its most recent party conference—it is hardly surprising that people do not feel their values are reflected in Reform UK.

However, our electoral system means that people vote for an individual to represent their area, not directly for a party. Our system is not set up automatically to call a by-election whenever an MP defects or is removed from a political party, or indeed when a party of government moves firmly away from a manifesto commitment. Nevertheless, the disillusionment that voters are experiencing points to something larger—a fundamental problem with how our democratic system currently works.

The Liberal Democrats believe that our political system needs fundamental change to restore the trust that voters have lost. First, we need to change the way we elect our MPs.

[Robbie Moore]

Before the hon. Member gets on to how we should change the whole system, I am keen to understand the Liberal Democrats’ view on the petition specifically. Should a defection trigger a by-election?

[Lisa Smart]

No. The Liberal Democrat position is that elections should happen on a regular basis. We would re-implement the Fixed-term Parliaments Act 2011, because we think it is healthy for people to know how long they are electing somebody for, rather than leaving the power in the hands of the Prime Minister of the day. I believe very firmly that the ultimate power should sit with voters rather than politicians, and that voters should know how long the term is. They should be able to boot people out at the next election, rather than having a special election that costs money and that may end up with the same result, but may not. We do not agree with the petition. However, we believe very strongly in people’s right to express their views through a petition.

We need to change the system and the way we elect our MPs. Under our current system, a Government can win roughly two thirds of the seats on roughly one third of the votes. Millions of people are represented by someone they did not vote for. Seats bear almost no relation to votes cast, and far too many people feel forced to vote for the person they dislike the least just to stop the candidate they really do not want to be elected. Proportional representation would change that. The Liberal Democrats have been advocating for a change in our electoral system for a long time. We already use proportional systems in Scotland, Wales and Northern Ireland. The vast majority of democracies worldwide use them.