What do former newspaper editor Andrew Neil, BBC newsreader Darren Jordan, EastEnder Ian Beale and Britain’s van drivers all have in common?

The answer is that none of them are as bright as Navy medic Catherine Doran, who finished as top scorer on a national TV challenge testing the UK’s IQ.

In fact, most of the country doesn’t measure up to the surgeon lieutenant commander, currently serving as a surgical registrar at Frimley Park Hospital in Surrey.

Catherine walked away from the BBC’s Test the Nation show as top of the pile, having answered 70 questions in a contest against fellow doctors, drivers, gardeners, triplets, redheads and models, plus a smattering of celebrities – all conducted on live TV watched by millions of viewers.

So – bright AND cool under pressure, then?

“After a short time you don’t realise you’re on TV – you’re more focused on answering the questions in time,” Catherine said.

The BBC approached the Royal Navy and asked it to provide three doctors for a ‘doctors team’ of more than 50 GPs, surgeons and consultants in a studio audience drawn from a cross-section of society, while viewers at home also took part in the show, presented by cult quiz-mistress Anne Robinson and Philip Schofield.

The IQ test focused not on general knowledge – like Mastermind – but mental dexterity, similar to the challenge posed by Admiralty Interview Board tests.

It obviously proved useful for the Navy medic, who notched up an IQ score of 143.

“I thought it was going to be a general knowledge quiz – which I’m not very good at. But IQ tests are not so much intelligence as whether your brain works in a certain way,” Catherine said.

“You could have knocked me out with a wet fish when I won. They’d had the spotlight shining in my face for ages – I just wanted them to turn it off. I didn’t realise it was on me because I’d got the highest score.”

The doctors proved the most intelligent group in the studio, way ahead of the celebrities and redheads, while the models lived up to stereotypes with the lowest average IQ score of 97.

But if you thought Catherine’s score was a Naval blip, think again - the Senior Service also had location on its side as well.

The residents of Plymouth are apparently the third most intelligent in the UK, after Cardiff and Aberystwyth. Portsmouth didn’t figure in the test, but near-neighbour Southampton came fourth.