"I was very worried about writing about it," she said. "Because if I made enemies, that would be my employment and my social life gone in one. But so far everyone seems chuffed that I've done the work and am speaking up for the area - though I'm not sure anyone's read the whole thing." There's a link in the first paragraph if you feel like rising to the challenge.
"Jon and I celebrated with curry and a bottle of champagne, then the following evening we spent singing in The Royal at Dungworth with a load of people who participated in the study."
The thesis concentrates on social singing, rather than music in which someone is paid to stand on a stage and others pay to listen, so it's not hard to imagine that a lot of people feel a kind of ownership of the subject matter - anyone whose done any social singing at sessions in Sheffield over the past five years, in fact.
"There's some confusion about community folk singing and why people enjoy it so much. I mean, if you took a picture during a session you'd probably find that everyone looked very sombre. But very often you'd also hear those same people saying afterwards that they'd just had one of the most enjoyable experiences they can remember."
Static crackles about dry wit and it being grim oop north are nearly audible on the line. "I'm not saying that all social folk singing is miserable by any means. It's just that everyone who will be doing it understands what's going on and it doesn't make much sense if you come fresh into it."
So you don't need to be grinning like a loon in order to enjoy yourself in Sheffield.
Which is probably just as well, because in a household containing two touring musicians and two small children - Polly and Jacob - it's hard to imagine she'd have the time. "When we first had Polly it was difficult. But we've worked out how to manage now."
So what's the secret? Full-time nanny? Accommodating parents-in-law? Prescription drugs? "Google calendar," she explains. "Everyone's got a copy. Me, Jon, our agents. There are still clashes but having it written down like that means it doesn't become a problem. I mean, we know what we're doing as far ahead as 2013.
"It's good in a way because it's a result of Jon being offered so much work. As a self-employed person it's your goal to reach a point at which you don't have to say yes all the time, to have a day when you can afford to pick and choose."
And what will she choose for herself? Will there be more academia? "I love ideas. I love reading other people's good work and reading things written by people I disagree with. Also making little connections in my head and having an original thought every once in while. I might apply to do a post doc in a year or so. And I thought about trying to incorporate my working life as a musician more closely into my studies. I'm still doing little bits of teaching.
"I think academia is very similar to being self-employed, in the sense that you're constantly creating your own way of doing things. I'm very much an Excel spreadsheet kind of a girl. I like lists and planning and I enjoy keeping my head on who's thinking and saying what in my field, making connections between them."
There's a new album on the blocks, ready to be recorded in September, following Looking Glass, which was out last year. "There's going to be a bigger band - although not quite so large as Bellowhead. My passion is for English trad folk, so that's what to expect."
Does she have a personal theory about what constitutes "folk music" then? And her answer, while probably true, reminds me that I'm talking to someone with academic detachment who is also nervous about making enemies. "I don't really get the label. There is so much that folk could mean that it seems kind of pointless to make those distinctions: lots of people create systems within which some things are allowed to be folk. But I can't be bothered to start thinking about it."
When she's relaxing she listens to Thomas Tallis, medieval music and Dolly Parton. "She came to Sheffield a few years ago but it was Jon's 30th birthday so I couldn't go. It was very inconsiderate of him."
And it would be remiss of me not to ask about her name but I think I can hear a sigh at the other end of the line as I raise it. "My parents didn't really notice [that it's a spoonerism of hay field]. But by the time I was about seven, people were starting to mention it. I've always thought that I should be a gardener really - like Pippa Greenwood, Bunny Guinness or Alan Titchmarsh. And then I've had a few people who assumed it must be a stage name. But no."
Many congratulations, Dr Hield, on a hard-won reward for all your academic endeavours.
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