Europe's biggest life and pensions mutual, Standard Life, thought to be worth about £15 billion sterling (€25.53 billion), said yesterday it was likely to agree to a request for a vote on demutualisation.

The decision is a surprise given Standard Life's staunch rejection of such moves in the past, including the rejection of a similar request in February.

Standard Life's board said it remained unanimously opposed to demutualisation, but one opinion poll shows that more than half of Standard Life's members favour demutualisation, including some of its biggest institutional policy-holders, such as Barclays Global Investors.

If a vote was in favour, Standard Life's demutualisation would be Britain's biggest ever, generating windfall payments of up to £6,000 sterling for many of its five million customers.

Such a move would also create a listed company with about £79 billion sterling in assets under management, enabling it to compete directly with Europe's largest life groups.

It would be ranked with the likes of Britain's Prudential, France's Axa, Switzerland's Zurich Financial, Germany's Allianz and the Netherlands' Aegon.

Standard Life chairman Mr John Trott told the group's annual meeting in Edinburgh that a request by pro-demutualisation activist Mr Fred Woollard for a vote appeared to be in order. A But Mr Trott said the board remained unanimously opposed to demutualisation.

"We received the members' requisition earlier today, and on first sight we believe it to be valid. If it is properly supported, we will convene a special general meeting of members to vote on the issue of demutualisation," Mr Trott told the meeting of 200 members.

"We will be advising members in the course of the next week when the meeting will take place, which will be within the next two to three months," Mr Trott said.

Mr Trott said the board discussed demutualisation last September and he added that the issue was regularly reviewed. "The board was unanimous then regarding staying mutual - and it is still unanimous," he said.

Mr Woollard and other members have stepped up their campaign for demutualisation in recent weeks.

A Standard Life spokesman confirmed shortly after yesterday's meeting that Mr Woollard's request for a vote appeared valid and a final decision would be taken after it was checked.

"We presume that Mr Wool lard has got his act in gear and that a special general meeting will take place," spokesman Mr Gordon Arthur said.

Mr Woollard, who is based in Monaco, told the meeting he welcomed the chairman's comments about the requisition leading to a full debate ahead of a vote on demutualisation.