Senior independent director
Corporate governance - UK Corporate Governance Code.
A senior independent director is an individual from among the independent non-executive directors of a company, under the UK Corporate Governance Code.
The SID needs to be free of any connections that may lead to a conflict of interest, and to have the necessary high degree of independence of character and judgement.
The SID acts as a sounding board for the chair of the board, and acts as an intermediary for other directors.