The Atlantic magazine has an interesting article entitled Rich kids study English. The data is American but I guess the findings may well apply to the UK too. Basically, the mean income of the parents of those who studied English is higher than those who did physics and chemistry degrees. The difference is not huge but the parents of physics and chemistry students earn about £10,000/year more.
So why is this? The article speculates that one reason is that the children of affluent parents may feel less pressure to do a more useful-looking degree than children who grew up in less financially secure homes. There are probably several factors at work here, not just one, but this may well be true. Another factor may be that there is more poetry and more theatre-going in more affluent families, and so more exposure to literature which inspires the kids to do English at university.
The article also links to a report by Georgetown’s (university in Washington DC, USA) Center on Education and the Workforce, which has data on what American graduates earn, as a function of what their degree was in. STEM (science, engineering and maths) graduates have a median earning of $43,000 (£28,000), just after graduation, while for arts graduates this is $29,000 (£18,000), a significant difference.
But these are kind of crude numbers. The page has a video of a short interview with one of the Georgetown authors of the study. He makes some very good points: these are averages, many arts graduates earn more than many STEM graduates; life is not just about the money, but a decent job is very useful; and students do better at degrees in subjects they really like. The video is worth a look, if you are thinking about doing a degree, or helping someone who is.