A friend who is a care worker employed by an agency has a moan to me about her work. Repeated 15 minute slots with a client followed by a frantic dash to another part of the city she lives in to do the same again. Care in a hurry, on the cheap. Welcome to home care for growing numbers in Britain: some of our most vulnerable people cared for by a growing number of overly stretched and underpaid workers.

Her first concern is about the always rushed, and often inadequate, care this way of working results in. But, to my initial surprise, she also expresses anger about not getting paid for the travel time that necessarily eats up a large chunk of her working day. She typically makes 40 journeys between clients a week, sometimes 50 (not counting her journey to and from work). "Surely", I say, "you must get paid for this travel time, or else I don't see how you would be getting paid the minimum wage". Indeed.

It's well known that social care is a notoriously low-paying sector, with the Low Pay Commission (LPC) estimating that one in four workers get paid below £6.50 an hour. Far less well known is that many of these workers get paid less than the national minimum wage. A new and authoritative report by Dr Hussein of Kings College London now reveals that, even under extremely conservative assumptions, there are at the very least 150,000 care workers getting paid less than the legal minimum - and quite probably far more.

How is it that the law of the land is being so widely flouted? My friend's pay slip sheds some light, exposing the chaotic system of pay that is the norm for many care workers, especially those working for agencies or private firms: constantly shifting hourly rates of pay - varying dramatically by client, length of each care visit, time of day, and day of the week. The opacity of pay rates makes it hard for those affected to fathom if they are getting their legal minimum; indeed the LPC has suggested that some employers don't themselves understand their own pay systems. A closer examination, together with records kept by my friend of her travel time over a period of a month, suggests there are weeks where she has clearly been paid significantly less than the minimum wage (though there are others where this is not the case). And the real story is worse than the pay slip suggests. She had to pay for her CRB check. There are no travel expenses even though travel is essential ('I couldn't afford to work if I didn't cycle'). Regular mobile phone use is essential to stay in close touch with the office - again, no expenses are paid. It just doesn't pay to care.

In theory the legal position governing the minimum wage is clear: workers should be paid for time spent travelling between clients (apart from between home and their place of work). Less clear is who in government or anywhere else is taking the lead for sorting this out and ensuring that the law is enforced. Awareness of this issue remains very low, this Panorama being an exception, and care workers are not anyone's political priority (can you imagine a Cabinet member, or for that matter the media, making a fuss about this issue as they did about graduate interns?).

All those responsible for this saga claim they have an alibi - which is cold comfort to those being under-paid. The LPC has repeatedly flagged up these sorts of working practices as a concern - though it has never taken it upon itself to make specific recommendations to government about non-compliance which in turn would require Whitehall to make a formal response. HMRC, which is responsible for enforcing the minimum wage, says that it takes any allegation of non-compliance very seriously. But it is yet to prioritise this issue as an area for its 'Dynamic Response Team' (lagging response times suggest that it could be, err, a bit more dynamic; though this is in part due to inadequate resourcing). The problems of the care sector currently fall behind unpaid internships in the queue for HMRC attention; though it is said that the care sector will receive priority at some point in 2012. For their part, local councils argue with some justification that they aren't receiving enough funds to cover the full cost of social care. And the Department of Health, who are ultimately responsible for social care in England, concede that Dr Hussein's report is a 'cause for concern' but maintain that pay is a matter for local employers so it's not really a question for them. All the while, the law on the minimum wage continues to be flouted.

There are lots of injustices in Britain that are so entrenched and complex that they would take a generation to turn around. This isn't one of them. The minimum wage is supposed to be a right, not a nice to have. So here's a resolution that we should stick to: let's make 2012 the year when every care worker gets what they are legally entitled to.