Troubled mutual Equitable Life is set to reveal details of a compromise deal with members to overcome its £1.5 billion pension liabilities by the end of the week.

The scheme aims to put an end to the uncertainty and instability which has dogged the society ever since it closed to new business last December after losing a legal battle in the House of Lords.

Details of the deal are not known but it is likely to involve guaranteed annuity rate (GARs) policy holders being given a rise in the size of their policy in exchange for giving up their right to guaranteed pension rates.

The society's problems stem from GARs, which became expensive to honour when interest rates fell in the 1990s.

It tried to get around this by reducing the final bonus it paid out but the House of Lords ruled against this, leaving the society with a £1.5 billion liability.

Equitable had been expected to offer GARs an increase of around 20 per cent of the value of the policy but this figure is now expected to be lower as non-GAR policy holders are also likely to be entitled to compensation.

The society has taken legal advice from Nicholas Warren QC, on whether non-GARs have grounds to sue the society for not revealing the full extent of the GAR liabilities when they bought their policies.

It is thought that they do have a claim against the society but the legal advice on the value of the claim is unclear.

Chief executive Charles Thomson has said non- GAR policy holders were likely to get some form of payment and talked about sharing the pain among members.

He also emphasised there is only one pot of money for the various settlements to come out of.

The compromise deal being sent out this week is a draft version for members and policyholder action groups to comment on before a final scheme, to be voted on by the end of the year, is drawn up.

The scheme needs to be approved by 50 per cent of all policy holders, representing at least 75 per cent of the fund's total value.