Exam watchdog Ofqual has announced that its chief executive is to leave the organisation less than three months after the resignation of its chair.

The double departure has led to questions about whether the body will retain enough expertise to regulate examinations effectively.

Isabel Nisbet, the chief executive, said she would be leaving Ofqual in March. Kathleen Tattersall resigned as chair and chief regulator in July.

The independent regulator lost the majority of the staff and expertise it would have inherited from the old London-based Qualifications and Curriculum Authority. They chose not to relocate to Coventry when Ofqual was set up there in 2008.

Ms Nisbet said this week: “I feel that Ofqual is in a strong place and ready to be a strong regulator in the new world.”

But a source at one of the big three exam boards claimed Ofqual faced a shortage of staff with a knowledge of regulation and education.

A former senior Ofqual employee said they thought the independent regulator now had less expertise than the exam boards it was supposed to be regulating.

Ms Nisbet admitted to The TES that it was not a “complete coincidence” that she and Ms Tattersall had decided to leave just after the coalition Government had taken office.

Ministers want to introduce linear-style A-levels with more involvement from universities and, in opposition, the Conservatives considered reducing the role of Ofqual by removing it from the A-levels accreditation process.

But Ms Nisbet says the watchdog needs to remain involved. “I believe there is a need for an independent regulator of important qualifications,” she said. “There needs to be an assurance, particularly if things change, that standards are being kept that is independent of the Government promoting the change and also independent of whatever organisation is developing the new qualifications.”

She said that if more changes were made, it was important they were piloted properly.

“It is always difficult, partly because the pace of change that any new Government wants is sometimes in conflict with the need to put all the checks and balances in place before the change.”

Ms Nisbet said she was proud of the transparency Ofqual had exhibited, but said it could have operated the controversial vocational Qualifications and Credits Framework with a lighter touch.

She is leaving to become the University of Cambridge International Examinations board’s senior adviser in the Asia Pacific region.

Ms Tattersall is a member of the Labour Party and in her resignation statement said her decision to leave was made in the context of the new Government “bringing a fresh perspective” to education policy.

Ministers have decided to remove the role of chief regulator from the office of the Ofqual chair and give it to the office of the chief executive, reducing the chair’s week from three days to two.

The posts of chief executive, with a salary of up to #163;120,000 a year, and part-time chair, to be paid #163;40,000, are being advertised.