Britain’s borrowing costs are rising faster than any other G7 country, with long-term debt yields hitting their highest level in nearly three decades amid investor unease over Labour’s economic strategy. The yield on 30-year gilts — the return investors demand for lending to the UK government — climbed to 5.64% on Monday, a level not seen since 1998. The surge followed a reshuffle of Sir Keir Starmer’s senior economic team, which brought advocates of wealth...