The term had been around for a long time, but was finally enshrined in law in 2000 when the Government published governors' terms of reference. It does seem to sum up the essence of the role of school governor.
All governors surely start from a position of friendship. Many, particularly parents, get involved because they wanted to give something back or go that extra mile in supporting the school for their child's benefit.
The most effective governing bodies are friends to the school, offering support from the practical to the professional, and giving constructive advice. Heads who value their governing body often describe them as a valuable sounding board for new ideas.
But the governing body does have to develop a critical edge. Full and frank discussion has to be possible if it wants to ensure a robust, strategic dialogue about the future direction of the school.
Critical friendship should not be seen as a threat or a restriction, nor should it be exercised unreasonably or aggressively. It should promote reflection on current practice in a sympathetic environment. In short, the governing body should be in a position to present an external, independent challenge as part of the function of holding to account.
Governors need to get this critical challenge right. Questions should be asked in the governing body about the reasons for new initiatives and changes - always with a weather eye on the school's vision and priorities.
Governors should challenge at a strategic level, not call into question matters of operational detail.
A confident body will give staff the space to operate effectively, knowing that they can be held to account . A confident headteacher and senior team will always invite questions and find challenges stimulating.
In day-to-day meetings, being an effective critical friend means making fine judgments about how to challenge at a strategic level without damaging relationships.
Think carefully about how questions are put, to whom and when. Your challenges should not descend into excessive scrutiny.