May 29, 2017 BOE ENGLAND AND WALES Re: Charity Commission Annual Return Guidance
Volunteers: Enter the peak number of publishers during the financial year ended March 31, less the number of elders who served as trustees.
This has been showing up already for sometime on the new Charity Commission website:
Then click on the 'People' tab
For Mill Hill: 18 Trustees plus 140 peak publishers = 158 total congregation members (at peak)