Mr Barrett's appointment caused controversy among shareholders

In a letter to shareholders, the UK's third largest bank said it had conducted a thorough selection process.

It added the independence of the post would not suffer as Mr Barrett had joined the group from outside.

The move sparked controversy as it is frowned upon under the Higgs Code - new guidelines for UK corporate governance.

Mr Middleton explained: "There is no reason to believe that his objectivity will be affected - as it might have been had his whole career been with Barclays."

"He fully understands UK corporate governance and the different roles played by Chairman and Chief Executive."

Shareholder muscle

The Association of British Insurers - whose members own more than 20% of UK listed companies - pushed Barclays into making the public explanation early.

Barclays had hoped to wait until its 2003 annual report, due out in March next year, to set out the reasons behind Mr Barrett's appointment.

Under the Higgs Code, designed to prevent Enron-style corporate scandals, a chief executive should not go on to become the chairman of the same firm.

However, the rules operate under a "comply or explain" policy, which means that if a company does not meet all the requirements it must set out why it has not done so.