The Charity Commission board member Peter Clarke is to stand down after he was named as the government’s preferred candidate to become chief inspector of prisons.
Clarke, a former head of the anti-terrorist branch at the Metropolitan Police, will step down "in due course" from his position at the commission, which he has held since 2013, in order to take up the new role, the regulator confirmed.
Commission chair William Shawcross expressed regret at Clarke’s forthcoming departure.
A commission spokesperson was unable to say exactly when Clarke will stand down or when a replacement will be appointed.
Clarke was named as justice secretary Michael Gove’s preferred candidate in a letter to the House of Commons Justice Committee, which will formally oversee the decision and hold scrutiny hearings with the candidate.
In the letter, Gove said although the scrutiny hearings were non-binding, he would "consider the committee’s conclusions before deciding whether to proceed with the appointment".
Before he retired in 2008, Clarke had worked in the Metropolitan Police for more than 30 years, and served as assistant commissioner and head of the anti-terrorist branch.
In his role as schools commissioner for Birmingham, he also led the investigation last year into the alleged "Trojan Horse" plot by Islamic extremists to infiltrate Birmingham schools.
Shawcross said his appointment was "good news for the country because Peter is immensely able and experienced".
He said: "It is, however, bad news for the commission. Peter has unrivalled experience and judgement. His mastery of complex issues is astonishing.
"He has contributed enormously to our work in many different ways. We shall all miss him."
A Charity Commission spokesman said: "The Cabinet Office will lead on the recruitment of his successor in line with the normal process once he has stepped down."