Welcome to the most unregulated labour market in Britain. Since 2008, au pairs have been specifically excluded from the legal definition of “worker” or “employee”: they have no right to the national minimum wage, they are not covered by health and safety regulations, there are no limits on their working hours and they have no legal right to holidays or any time off.

In theory an au pair is a young person, normally from another EU country, who will do 25 to 30 hours of childcare and housework in exchange for room, board and “pocket money” and is treated as a member of the family. In practice, the working and living conditions of au pairs often fall far outside these expectations. Rather than being young women on a fun gap year aboard, too often au pairs are a hidden, exploited group of low-paid migrant workers. When you add to this the dominance of unregulated online agencies and high rates of youth unemployment in many EU countries that au pairs come from, it’s easy to see how problems might arise.

Research I undertook with another academic, Nicky Busch, found that many au pairs are carrying out long hours of work, for very low pay, often in conditions that are far outside the traditional imaginings of the role. In the absence of official data, we analysed online ads and found that the average au pair was expected to work 38.7 hours a week (hardly a part-time job). One in 10 ads were looking for 50 hours or more, with one advertising an 80-hour week. The average “pocket money” offered in return was £108 per week, but it was striking that there was no correlation between the hours to be worked and the amount offered. Some hosts offered none at all, seeing a room in their home as payment enough, and some ads didn’t even offer a room, wanting a “live-out au pair”, or for them to sleep on the sofa.

It was common for ads to set out duties that went beyond “help” with childcare and housework, including shopping, cleaning windows, caring for relatives’ children, waitressing or cooking for dinner parties, gardening, teaching a child a language, and more. One ad stated that the family wanted an au pair to help with their business as well as “helping to run the home”. Another offered “use of horse and kayak” as part of the remuneration package. Worryingly, we found that many au pairs are expected to do work that in the past would have been done by a qualified nanny, including providing sole care for babies and infants.

Interviews with au pairs reinforced this picture of “au pair” being a catch-all term for low-paid domestic work. They told us about long hours of housework, overwhelming childcare duties, and a general expectation that they could sort out all the stresses and strains of modern life for their host families.

Many of them did have good things to say about their time as au pairs and the families they lived with, but we also heard lots of comments about being treated “like a servant”. Examples included being denied opportunities to attend language classes or other activities, always being on call and being given inadequate space and even inadequate food. One summed up this grinding day-to-day denigration with a story about fruit juice. When her host mother noticed some juice missing from the fridge, she told her: “This [juice] is really expensive. If you want some juice you can tell me and I’ll buy you some cheap juice.” So much for being treated as an equal.

While Uber drivers and Deliveroo couriers are left without rights because they are deemed to be self-employed, au pairs’ work is quite simply defined as not being work. Instead they are considered to be “helping” their host families and involved in cultural exchange rather than labour, no matter how many hours of work they do or how arduous that work is. When you live with your employers, negotiating better conditions – or even just better juice – is not easy.

While the prospect of the stream of au pairs drying up post-Brexit has created some recognition of how important they are, we should also pause to consider why so many families are reliant on an unregulated, insecure and often exploited group of workers. The British Au Pairs Agencies Association has released new guidelines on what an au pair should be. At the very least, the government needs to adopt these and enforce them. But a bigger step would be to recognise childcare and housework as real work.

• Rosie Cox is a professor of geography at Birbeck, University of London, and co-author of As An Equal? Au Pairing in the 21st Century