The vote was in Makerfield. The first invoice landed in the bond market.

The economic consequence of last night's result showed up where it always shows up first: in the price of British government debt. As Andy Burnham's Makerfield win cleared his path to challenge for the leadership, gilt yields ticked up again and sterling slipped, extending a jittery few weeks for UK assets. This is the market doing what it does with political uncertainty — charging more to hold it.

Britain was already an expensive place to be a government. UK long-term borrowing costs are the highest in the G7; earlier this spring, amid the leadership turmoil and the energy shock, the thirty-year gilt yield touched levels not seen since 1998 and the ten-year reached its highest since 2008. The pound has been grinding lower. The fear investors name is specific: Burnham is read as standing to the left of Starmer and his chancellor, with talk of tens of billions in extra borrowing for housing and infrastructure, and the bond market has a long memory of what unfunded plans did in 2022.

Here is the part worth holding onto, because the temptation today is to draw a straight line from a by-election to your money. Several economists are urging caution. One at ING argues that oil prices, not politics, are still the main driver of gilts right now, and that the market is pricing a risk premium for uncertainty rather than delivering a verdict on a Burnham government that does not yet exist. The sharpest question, he notes, is not who lives in Number 10 but who would run the Treasury next door. The move is real; the interpretation is not settled.

For the household the transmission belt is the mortgage. Fixed mortgage rates are priced off gilt yields, not directly off the Bank Rate the committee held yesterday. So when political risk pushes gilt yields up, the fixed deals on offer can drift higher even though the Bank has not moved. If you are remortgaging into this, the thing nudging your quote this week may be the politics as much as the policy. This is information, not advice.

A government's borrowing cost is, in the end, a measure of how much the world trusts its story about the future. Britain is paying a G7-topping premium on that story at exactly the moment its politics has stopped telling one and started arguing about the narrator. The bill for the uncertainty is real — and it is partly itemised, quietly, on a mortgage offer.