A string of pension buyouts involving FTSE 100 companies is expected over the next few months after Lonmin, the London-based miner, became the first blue-chip company to offload its pension scheme risks in a deal with Paternoster, the specialist insurer.

Mark Wood, Paternoster’s chief executive, said that trustees of several FTSE 100 pension schemes were already “deep in the process” of looking at shedding scheme liabilities. “I think we will see four or five FTSE schemes taking the buyout route over the next nine months,” he said.

Lonmin’s pension scheme is relatively small, at “comfortably less than £1 billion”, according to Mr Wood. However, overcoming the psychological hurdle associated with a FTSE 100 pensions buyout is likely to spur other trustees’ confidence, he said.

Clive Wellsteed, a partner in at Lane Clark & and Peacock, an actuarial consultancy, said: “The market will continue to accelerate as companies and trustees grasp the opportunity now available.”

The Lonmin deal comes after buyouts involving Emap, the publisher, and P&O, the ports operator owned by DP World, of Dubai. Many companies want to end the relationship with their defined-benefit pension funds because of uncertainty created by volatile stock markets and rising life expectancy.

Yesterday, Mercer, the pension consultant, said that some of Britain’s top companies had raised pension scheme life-expectancy assumptions but were still far off regulatory guidelines.

Data from 30 companies in the FTSE 350 showed that they increased life expectancy assumptions by an average of six months in 2007, adding about £8 billion to pension liabilities.

However, the figures suggest that mortality assumptions are still far less than those recommended recently by the UK Pensions Regulator, which recognise a recent rapid increase in lifespans, Mercer said. The regulator has proposed that companies adopt the most conservative projections, which assume that the average 65-year-old man retiring today will live to 90.

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