Shawbrook CEO Pyman takes break following strain of IPO

* Pyman acting on medical advice

* Bank says CEO worked extremely hard prior to IPO (Adds comment from spokesman, details)

LONDON, May 21 (Reuters) - New British bank Shawbrook said Chief Executive Richard Pyman had taken a temporary leave of absence due to illness and appointed finance chief Tom Wood as interim CEO.

The bank said Pyman, who has served as chief executive since April 2014, would take a break on medical advice having come under intense pressure in the run-up to Shawbrook's initial public offering (IPO) in London last month.

"Richard is utterly dedicated to Shawbrook and has been working extremely hard in recent months in particular. IPOs are highly intensive processes for everyone involved and undoubtedly added significantly to his workload in recent months," a spokesman said.

Shawbrook was founded in 2011, one of several "challenger banks" to emerge since the financial crisis as the government and customers alike sought alternatives to Britain's "Big Five" lenders - Lloyds, HSBC, Royal Bank of Scotland (LSE: RBS.L - news) , Barclays (LSE: BARC.L - news) and Santander UK.

Shares (Frankfurt: DI6.F - news) in Shawbrook have risen by 17 percent since the bank's stock market listing and closed on Thursday at 340 pence, valuing the business at 850 million pounds.

Shawbrook said Wood would be assisted in Pyman's absence by Stephen Johnson, who has recently received regulatory approval to become deputy chief executive.

Shawbrook said net lending to customers had increased by 11.6 percent to stand at 2.6 billion pounds ($4.1 billion) at the end of March. It said it had made an encouraging start to the year and was on track to achieve its 2015 expectations.

($1 = 0.6379 pounds) (Reporting by Matt Scuffham; Editing by Steve Slater/Mark Heinrich)