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Should MPs who switch parties be forced to face a by-election? - Parliament Matters podcast, Episode 127

23 Jan 2026
Image © House of Commons
Image © House of Commons

In this episode, we ask whether MPs who switch parties should be forced to face a by-election – and what this month’s spate of defections says about representation, party power and voter consent. We also unpick a dizzying week in British and global politics as “hurricane Trump” batters the post-war order, testing the UK-US alliance and raising awkward questions about NATO, defence spending and procurement. Plus: the Lords’ push for an under-16s social media ban, Chagos ping-pong, and stalled bills in Westminster.

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With Westminster watching Washington’s every swerve, we explore why Keir Starmer’s most outspoken pushback on tariffs and Greenland matters – and why making big foreign-policy statements outside the Commons still rankles.

In the Lords, a proposed ban on social media for under-16s forces the government into damage-limitation. Is the government’s promised consultation a serious route to action, or simply a way of kicking a difficult issue into the long grass? We look at how enforceable such a ban would be, how it fits with the existing Online Safety Act, and the political and constitutional tension of tightening access at 16 while simultaneously debating votes at 16.

We then turn to a growing list of legislative headaches: the Hillsborough Law stalling again amid disputes over national security carve-outs; renewed procedural drama over the Chagos Islands Bill, how the financial privilege of the House of Commons blocks Lords amendments, and what options Peers have left. We also ask why the bill to remove he remaining hereditary peers appears to be stuck in a curious parliamentary holding pattern.

Finally, we focus on party switching, the e-petition calling for automatic by-elections for defecting MPs, and whether such a rule would enhance democratic accountability or simply hand party machines a powerful new weapon against dissent. As we were recording, news broke of an actual by-election, with Andrew Gwynne MP announcing his resignation on health grounds – a vacancy that could trigger a contest with significant implications for Labour’s internal politics and Sir Keir Starmer’s leadership.

Please note, this transcript is automatically generated. There may consequently be minor errors and the text is not formatted according to our style guide. If you wish to reference or cite the transcript copy below, please first check against the audio version above.

Intro: [00:00:00] You are listening to Parliament Matters, a Hansard Society production supported by the Joseph Rowntree Charitable Trust. Learn more at hansardsociety.org.uk/pm.

Ruth Fox: Welcome to Parliament Matters, the podcast about the institution at the heart of our democracy, parliament itself. I'm Ruth Fox.

Mark D'Arcy: And I'm Mark D'Arcy. And coming up this week.

Ruth Fox: Battling the chaos. Parliament braces itself against Hurricane Trump.

Mark D'Arcy: The Hillsborough law, social media bans, and hereditary peers. The awkward legislative questions stacking up in Keir Starmer's parliamentary in-tray.

Ruth Fox: And should turning your coat mean calling a by-election. Is it right that MPs can change parties without asking the voters?

Mark D'Arcy: But first, Ruth, it's been to put it gently a dizzying week in not just British, but [00:01:00] in world politics with, as you described it just now, Hurricane Trump blowing against all the foundations of the post-war order. Is Britain really gonna still be an ally of the United States if it does go in and seize Greenland?

Ruth Fox: Now there's a deal, possibly.

Mark D'Arcy: Yeah, there is the concept of a deal of the future of Greenland, apparently. And nobody knows what's gonna happen next because it's entirely possible for this president to wake up and decide to do something completely different to his last announcement and just presented as all part of his art of the deal brilliance.

So what you've got is a situation where there's certainties that have shaped the post-war order for Britain, basically the military alliance with America, NATO, Atlanticism, all those dominant currents in British foreign policy, security policy, nuclear policy have just evaporated. Nobody knows what's gonna happen next with American policy.

Nobody knows whether we're going to be left bobbing in its wake or [00:02:00] totally alienated by it. And so Keir Starmer has to get up in Parliament every week and try and keep things calm. And this week I think the strain was beginning to tell. Full transcript →

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