𝓤𝓷𝓲𝓽𝓮𝓭 𝓝𝓮𝔀𝓼

Markets are significantly under-pricing the risk to sterling from a potential leadership change that could see Greater Manchester mayor Andy Burnham replace Keir Starmer as prime minister, a leading City analyst has warned. With just two weeks until the critical Makerfield by-election on June 18, Ebury’s head of market strategy, Matthew Ryan, has issued a stark alert over the fiscal dangers of a Burnham premiership.

Mr Ryan said sterling faces “material downside risk” as investors brace for a sharp leftward shift, higher public spending, tax rises, and increased gilt issuance. He explained: “The May local elections have accelerated an already precarious political situation for Sir Keir’s Government. While a formal challenge has not yet materialised, we see this as more a matter of arithmetic, rather than a genuine lack of appetite among leadership hopefuls.”

Mr Burnham, the clear frontrunner in betting markets with an implied probability of around 60%, is eyeing a swift return to Westminster. As a sitting mayor, he requires a parliamentary seat to formally contest the Labour leadership.

Mr Ryan said a victory in the Leave-voting Makerfield constituency – where Reform UK has made inroads – would “more-or-less clear his path to Downing Street”.

The only poll so far shows Mr Burnham with a narrow three-point lead, meaning the outcome is far from certain. A strong performance would heighten fiscal concerns, while a poor result would signal deeper Labour turmoil. Ryan noted: “Neither is a particularly palatable result for UK markets.”

Ebury’s analysis paints Mr Burnham as the candidate posing the greatest risk to sterling among realistic successors. His track record and instincts point towards a “material loosening in spending, funded by borrowing and further taxation on capital and higher earners”. This comes at a time when the UK has wafer-thin fiscal headroom, a rising debt-to-GDP ratio, anaemic growth, rising inflationary pressures, and an ageing population.

Mr Ryan warned: “The problem is that the UK can ill afford such an experiment.” He highlighted Mr Burnham’s past dismissive attitude towards bond markets – since softened – which “the bond vigilantes will not forget, and will punish accordingly”.

The report warns that a Mr Burnham victory would represent the most significant leftward shift among succession scenarios, prompting markets to rapidly reprice UK fiscal risk. Sterling has already acted as a “reliable proxy for UK fiscal credibility”, underperforming alongside gilts amid political anxiety. The spread between 30-year gilt yields and G7 peers has widened markedly this year, amplified by political uncertainty.

Other contenders, such as Ed Miliband and Angela Rayner, are also seen as carrying high market risk due to their soft-left positions and spending ambitions. Only Wes Streeting, viewed as closest to the current centrist approach, is considered modestly supportive of the pound.

Mr Ryan emphasised that even if Sir Keir clings on – with Polymarket giving him just a 30% chance of lasting the year – upside for GBP will remain capped. Persistent political risk premium from leadership uncertainty and a probable policy pivot to the left will continue weighing on sentiment.

Mr Burnham’s ambitions to return to Parliament and challenge for the top job have been an open secret. The former shadow home secretary and leadership contender has built a strong personal brand as Greater Manchester mayor, positioning himself as a champion of the north and working-class interests.

His support among Labour members is seen as formidable, potentially enough to overcome MP reservations and trigger a contest.

The Ebury note comes as gilt markets already price in significant political risk. Mr Ryan cautioned that a left-leaning successor would test fiscal rules, boost bond issuance, and likely lead to steeper yield curves and sustained sterling weakness – echoing the swift repricing seen during the 2022 Liz Truss mini-budget turmoil.

With the by-election looming and Mr Burnham appearing on BBC Question Time, the coming days could prove pivotal for both Labour’s future and the value of the pound. Markets, currently complacent about the delayed timetable for change, may soon be forced to confront the full implications of a Mr Burnham-led government.