Ray Hall, the director of bureau at the Audit Bureau for Circulations, has suddenly left the organisation.
His departure came on the same day as a meeting with the chairman of the ABC Geoffrey Copeman on Thursday last week.
Austen Hawkins, head of sales & marketing for ABC, says: “There was a mutual agreement that Ray and the ABC should go separate ways.”
Head of operations Anthony Peacham has taken on the post of director of bureau on a temporary basis with additional support from Copeman.
It is understood that the post will be advertised.
Hall has spent three years at the ABC, initially as director of marketing and communications at the then ABC subsidiary Verified Free Distribution.
When ABC was restructured in 1996, Hall became director of bureau.
As well as overseeing the restructuring, Hall also played a leading part in resolving the legal dispute involving The Daily Telegraph and News International over circulation figures in 1997.
At the end of January moves were made to amend the rules in respect of exclusion days, bulk sales and the tracking of lesser-rate sales.
But the ABC council was unable to ratify the new rules on bulk sales because they were deemed impracticable.
The proposed rules had provided for publishers to gather evidence on footfall – the number of people visiting a place where copies of the titles are available.
At the end of March, the ABC council approved revised rules on bulk sales, but with minor points outstanding.