Steve Jenkins, chief executive of Nautical Petroleum, whose share price fell more than 10pc to 399¾p, claimed the company's heavy oil portfolio, which has substantial tax breaks, would help protect the company from the impact of the levy. However, he added: "It's bound to affect investment in the industry. What it needs is predictability and if the UK keeps tinkering it doesn't look good. It's going to have an effect right the way down the food chain. It's not good news at all."