I can't tell if this is in the article as it's paywalled, but a company in York recently put up an advert for £20k/year for Cobol programmers with no programming experience required, doubling at the end of the training period.
(Being paid to learn a skill from scratch does sound pretty objectively good, though.)
In the UK, £20k is below average for a junior programmer straight out of university. For example, we've just employed such a person for £25k, in a PHP role.
However, the jump to £40k, provided that the qualifying period wasn't too long, would shortcut several years of career development for a recent graduate. I'd say that's a good deal, except that I'd be concerned about the long term prospects for a COBOL programmer in the UK.