With the announcement that former magistrate Sarah Pochin will be Reform UK's candidate in the all-important Runcorn by election, how important is the vote for leader Nigel Farage? Although the by election - expected to coincide with May's local elections - has Reform tipped to win, Farage has sought to manage expectations.

This makes sense. Although the vote will test how genuine Reform's poll numbers really are and offer the chance to put the Rupert Lowe row behind the party, Farage's enemies both within and without will pounce if Reform loses. In truth, falling just short of victory but still closing the 15,000-odd-majority Labour achieved last July would still be a massive achievement. Yet expectations are high.

Labour won't be resting easy either and Farage knows it. While Reform is primarily seen as a challenger to the Tories, Farage's party is a major threat to Labour as well, not least in northern seats like Runcorn.

Sir Keir Starmer's party will see Runcorn as a must-win, with a victory for Reform a huge blow to the PM's authority as he seeks to push through unpopular budget plans and faces rebellion on the backbenches.

And though the Tories are without a hope of winning,a decent showing could at least strengthen under-fire leader Kemi Badenoch's authority as Reform pushes her party into third place in national polling.

Runcorn then is a big deal for all main party leaders. With all major candidates now declared, expect a tough and robust campaign with Reform looking to capitalise on recent polling.

Expect immigration, and law and order, to figure heavily in the campaign, with much made of Reform candidate Sarah Pochin's magistrate background. Though local issues will be front and centre, the backdrop is a national picture where Reform is upping the ante and shaking the status quo.