One of the North Sea’s largest oil and gas projects has been plunged into uncertainty after its operator announced it was slowing down investment in light of “fiscal and regulatory uncertainty”. Neo Energy had planned to start work on the £900m Buchan project – expected to produce a peak of 35,000 barrels of oil a day – in 2027. But now the firm, which also owns 50 per cent of the project and is a top five producer in the North Sea, has said it will “materially” slow down its investment activities,…