By Shadia Nasralla LONDON (Reuters) – The British government stood firm on its windfall tax on the oil and gas sector in a meeting with industry executives on Friday, two sources with knowledge of what was discussed said. Finance Minister Jeremy Hunt rebuffed requests from North Sea oil and gas executives to include a mechanism in the tax to reflect falls in oil and gas prices, although a future revision was not ruled out should prices slump, the sources said. Hunt last month announced plans to boost the Energy Profits Levy (EPL) on oil and gas companies from 25% to 35%, bringing the total tax…