The rules governing who can stand for election as chairs of committees must be changed, in order to prevent former secretaries of state and ministers chairing committees which scutinise work which may have occurred under their own leadership. This potential conflict of interest must be addressed.
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Select committees conduct important work holding the government to account, and their independence must be guaranteed (as much as is possible, given the pool of potential candidates for the position of chair).
For example, Jeremy Hunt was Health Secretary from 2012-18, and is now chair of the Health and Social Care Select Committee. It is questionable whether Mr Hunt is able to lead proper scrutiny of government health policy and practice when he has been responsible for this policy area.