Mike Clasper, the chief executive of BAA, is on course to walk away from the airports operator with a total package including pension rights that is valued at almost £10 million.

Mr Clasper, who is understood to have been unhappy about running a subsidiary company under new owner Ferrovial, is expected to leave BAA by the end of the week, despite the Spanish group wanting him to stay.

However, Mr Clasper will stay on at BAA, which runs Heathrow, Gatwick and Stansted airports, in a part-time consultancy role.

As it confirmed Mr Clasper's departure this afternoon, BAA named Stephen Nelson, its retail director, as his replacement. Mr Nelson joined BAA last September from J Sainsbury, the supermarket group, where he was marketing director and a member of the operating board.

Mr Nelson joined the BAA board in April.

According to BAA's most recent annual report, Mr Clasper is entitled to a payment of up to 12 months salary and bonus, which last year totalled £1,081,000.

As well as owning 54,861 shares in BAA worth £511,852 at today's 933p price, Mr Clasper holds 488,730 options under the executive sharesave scheme that are currently valued at more than £4.5 million.

Mr Clasper will not make a direct profit of this amount when he exercises the options because of strike prices set at between 476p and 587p. His profits will be in the difference between the strike price and the 935p price agreed for the Ferrovial takeover.

In addition, Mr Clasper has a pension with a current transfer value of £3.59 million. Together, the entire package is valued at £9.74 million.

BAA declined to comment on Mr Clasper's departure or on the value of any payout he may secure.

Having joined BAA in 2001, Mr Clasper became the chief executive in 2003 and drove a significant strengthening of its core airport operations. Alongside Marcus Agius, the Lazard investment banker who chairs BAA, Mr Clasper also drove the group's staunch defence against Ferrovial's initial assaults.

The two men managed to bring about an increase in the final agreed price paid by Ferrovial from the initial 810p to 950.25p, including a 15.25p payable dividend.

It is thought that Mr Clasper will pursue other executive positions following his departure.

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