Staff governors are a vital part of a governing body. The role is different from a union rep. A staff governor is not a staff representative but a representative member of staff. Staff governors cannot be mandated by the staff to vote in a certain way but most vote for what is best for the school. Staff governors will be party to confidential information and must not share it especially if discussed in Part 2. This can be very difficult if for example it includes a restructure which may include proposals to make colleagues redundant.
There is though a mis-conception that staff governors are not full governors and they get excluded from many discussions (such as staff restructures). I have even heard of some governing bodies making staff governors leave for all of and every Part 2 of a meeting.
Staff governors should leave a governing body meeting if they have an interest greater than other staff.
A useful document is "Governor meetings: attendance, voting rights and conflicts of interest". Please click here to read it.