But there was also speculation that several big UK banks that had previously expressed interest in doing a deal with Bank of Scotland would now be dusting off their dossiers. Both HSBC and Barclays are understood to have made informal expressions of interest over the past year to BoS.
Standard Life said it is reviewing its stake because it has become too large for its investment portfolio.
"Standard Life continues to have confidence in Bank of Scotland's future prospects and strategies, but we nevertheless believe it could be in the interests of our policyholders to rebalance our equity portfolio by realising some or all of our stake in Bank of Scotland," said Scott Bell, managing director of Standard Life.
It is also assumed, given the pressures for consolidation in the life mutual sector, that the Scottish giant is getting its books in order for any strategic moves it may decide to make. Standard Life has appointed Lazards to advise on the sale, while the Bank of Scotland is being advised by Schroders.
Standard Life initially bought the 32.5 per cent stake in Bank of Scotland from Barclays in 1985, paying the equivalent of about pounds 250m. It is now worth approaching pounds 1bn, and accounts for about 7 per cent of Standard Life's UK equity portfolio.
Initially there had been hopes that the investment would provide the basis for closer commercial co-operation. This never bore fruit, leaving a purely financial investment which Standard Life decided is too large.