The UK’s Financial Ombudsman Service (FOS) chief executive Natalie Ceeney is to step down from her role after a spell of four years.

Following Ceeney’s departure, deputy chief ombudsman Tony Boorman will take the helm at the FOS for the time being.

Ceeney joined the FOS in March 2010 from the national archives, where she was chief executive and keeper of public records.

Prior to this, she was formerly director of operations and services at the British Library and led strategic consultancy projects across a range of industries at McKinsey & Company as well as working for the NHS as a manager for four years.

Under Ceeney’s leadership the ombudsman service has trebled in size and has overseen massive expansion to deal with complaints about the mis-selling of loan insurance by banks.

Most of the complaints were about the mis-selling of payment protection insurance, a scandal that has cost banks in excess of £17 billion pounds in compensation.

Earlier, Ceeney was criticised by advisers for lacking financial services expertise.

FOS chairman Sir Nicholas Montagu, who made the announcement, said: "In the close to four years since joining, Natalie (pictured) has taken the service from dealing with an annual workload of 150,000 cases to over 500,000 cases – with the organisation trebling in size under her leadership in response to the challenges of PPI.

"So having just received our millionth new PPI complaint, Natalie feels that now is the time for her to move on – as the ombudsman service itself starts out on a new set of challenges, building on the foundations for change laid under Natalie’s leadership," he added.