Exit survey - how to be honest?

[YellowFlamingo]

I've been given an exit survey as governors are investigating why so many staff are leaving (over half of the primary school).
The survey has both rating scales and open questions as well as an additional comments section.
There are some positive things about the school and some negatives. In particular, most staff are going because of a bullying, rude, patronising deputy head who joined around 5 years ago.
Any advice on how to fill this in usefully? I want to state the issues so that they can be addressed for future staff but I don't want to be unprofessional or moany.
It has the option to remain anonymous or give your name.

Don't assume that if you don't give your name that it will be anonymous and remember your need for a reference.

I'd put down stuff like workload, communication issues in more general terms than name specific staff members. They may be able to join the dots anyway.

Exit surveys are pointless because no one is ever completely honest.

Don't assume that if you don't give your name that it will be anonymous and remember your need for a reference
This.
Remember, you're in education. It isn't honest, it isn't fair and you're lucky if you come out alive.

I'm a Governor and we treat exit surveys as confidential to the Governors. We then decide how and what to share. It helps us decide what we should be doing. If it's done like this I would be honest. (although if your governors have half a brain they would have twigged on already)