For the last two and a half years Unison has been at the centre of union opposition to the coalition's austerity programme and it organised last November's mammoth strike. In some areas its campaigning has been successful (one of the under-reported stories in the autumn statement was George Osborne's decision to abandon regional pay).
But the austerity programme continues. I'll ask about what has worked for Unison, what hasn't, and what comes next. I'll ask about relations with Labour and the future of public services generally. But I'd like to hear your suggestions for questions too.
As you can see from its website, Unison has taken strong positions on a range of public service issues. Here's the speech that Prentis gave to the TUC conference and here's the speech he gave to the Labour conference. And here's a perceptive profile of him.
I won't be able to use all the questions you suggest, but it is helpful to get ideas from others and it is useful to know what topics you find particularly interesting.
