I've not seen the original journal article, but based on the Guardian report, the study is interesting not in what it covers - absolutely nothing new there - but rather in what it chooses to ignore.
Firstly, that those teaching in Further Education or schools are paid even less. Ah, just a hint, then, that status might have something to do with it?
And secondly, that silence that we've all come to know and love: those employed in Higher Education, but not blessed with the luxury of academic working conditions and perks. Yep, the "non-academics" that are cursed in our particular University as "PASS" staff.
The study, it appears, stopped short of looking at those professionals that are conveniently invisible to academic staff seeking to grumble about their own lot - the "academic-related" staff who are also creators and purveyors of knowledge, whose hours are at least as long as the rather paltry 47 per week average of the academics (what luxury! that's a mere nine and a half a day excluding weekends!) but who lack the status, the recognition and - to get back to the point of the article - the remuneration levels of their academic colleagues.
Some of these staff have options outside of Higher Education, it's true - unlike academics, who are limited to universities, research councils or consultancies for employment, academic librarians could find employment at... hmmm. There must be somewhere else....? The two or three national libraries, perhaps, where State salaries are likely to be of the same order? Academic computing, e-learning and educational technology staff could always relocate to... private consultancy? Research, or scientific / technical officers might in some cases find a home in industry, depending on their disciplinary location, but no more or less likely than the academics in those disciplines. And if an Electrical Engineer, say, is choosing a career in academic rather than one in industry, why should her / his bleat for more money be given any more weight than the technical officer who is told "if you can earn more out there, why don't you leave and get a job out there instead of asking for more money here?"?
But of course, the study is silent about such matters. Conducted by academics, who control the field of Higher Education Studies both as the practitioners and as the subjects, why should such a study seek to undermine the interests of those it seeks to serve, even if the resulting omission leads to knowledge that can, at best, be described as partial (in all senses of the word)?