No mention of what counts as a "cup" of coffee in the abstract you link to. Given that it's a British study, they're likely rereferring to a UK "cup" (284ml), but, really, who knows?

Also, given that they're looking at coffee vs no-coffee vs non-caffeinated, I would have expected a mention of mg of caffeine. (typical in the US is 95mg in an 8oz (237ml) cup. But there's a huuuge variation in caffeine levels. Great explanation here: https://www.caffeineguide.com/many-mg-caffeine-cup-coffee/

TL,DR: not a particularly useful study - at least the parts visible to the general public.