BP's £12.6bn pension fund, the biggest in the country, has slipped from a funding ratio of 120% to 96% of its liabilities in the past 12 months, according to its annual accounts. The oil giant says the fall, caused by the drop in value of its stock market investments, will not force it to close its scheme to new members, although several other Footsie companies have taken this step and blamed FRS 17.