Andy Hornby, the man running HBOS when it had to be rescued by Lloyds bank in 2008, has unexpectedly quit his £1m-a-year job as chief executive of healthcare group Alliance Boots with immediate effect.

Andy Hornby, the man running HBOS when it had to be rescued by Lloyds bank in 2008, has unexpectedly quit his £1m-a-year job as chief executive of healthcare group Alliance Boots with immediate effect.

Sources close to Hornby insisted that his surprise departure was his own choice. City analysts suspected a personality clash at the top of the company.

Hornby, aged 44, indicated that he needed to step back from the demands of corporate life. "After an intense last five years as CEO of two major companies, I have decided to take a few months' break and, having discussed it with the board of Alliance Boots, to stand down from my post as group chief executive," said Hornby in a statement.

He had joined Alliance Boots in June 2009, just months after his tenure at HBOS ended with the stricken bank being rescued by rival LLoyds TSB.

Stefano Pessina, the executive chairman of Alliance Boots, said Hornby left "with our very best wishes for the future".