In recent months the bank has been under pressure from investors. In September, Barclays said it would take a pounds 250m charge this year for losses on Russian securities at its Barclays Capital unit.
"It's a very big move," said Graham Campbell, a director at Edinburgh Fund Managers. "His leaving suggests that problems are more deep-seated than just a few trading losses."
The past three years have been the toughest for Mr Taylor, a former journalist who joined Barclays after a stint as chief executive of Courtaulds. Barclays' losses this year in Russia were preceded by charges last year to sell BZW, and charges the year before as the securities unit hired top talent.
Barclays also said it expected 1998 pretax profit of not less than pounds 1.9bn, lower than some estimates, sending the shares sliding 131 pence or 8.8 per cent to 1,357p.
Since Mr Taylor took over, Barclays shares have gained 110 per cent, underperforming the FT-SE Bank Index of Britain's 13 biggest banks, which climbed 126 per cent.
"The job is getting tougher and times are getting tougher and he thought someone with recharged batteries could take it further," said Sir Peter.
Mr Taylor does not have a job waiting for him at another company, said Sir Peter. Still, analysts said he may be interested in joining the Government. He is close to Tony Blair and he conducted a study on how to reduce dependence on welfare last year.