I checked Charity Commission, and found this...
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4. having clear written terms of reference for committees of the board, advisory groups and panels, and for all delegated authority, which provide sufficient delegated authority and clear boundaries to allow officers, committees, staff, volunteers, consultants and agents to discharge their duty effectively and which are regularly reviewed and updated
5. periodically reviewing the organisation's committee, advisory group and panel structure to ensure that it continues to meet the organisation's governance needs
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Mike Peel suggests that material is added to his draft concerning how the governing authorities view this. I would suggest a quick call to the Charity Commission would be a good thing....
Gordo