Being plain has been pretty good for me': Doc Martin star Selina Cadell on her looks and best friend Sigourney Weaver

he face is tantalisingly familiar, as is the name. Doc Martin fans will recognise Selina Cadell as Mrs Tishell, the overwrought pharmacist in a neck brace who had the unrequited hots for Martin Clunes in the ITV show.

Yet she’s also the spitting image of one of TV’s best-known comedy stars.
Anyone who enjoyed the 80s sitcom Hi-de-Hi! will have spotted her resemblance to Simon Cadell, the holiday-camp comedy’s late-lamented leading man who played posh-boy misfit Jeffrey Fairbrother, the object of Gladys Pugh’s rebuffed affections.

Like her mentor brother, she's equally adept at straight drama, taking the title role in BBC1's glossy new 90-minute mystery adventure The Lady Vanishes

Selina is Simon’s equally gifted little sister, and looks more like him than her non-identical twin Patrick, a commercials director.
‘Simon was a huge influence on me, giving me so much advice; he was very, very special,’ she says. Her beloved big brother died 17 years ago this month, aged just 45, after being diagnosed with non-Hodgkins lymphoma following triple heart bypass surgery.
He was also a heavy smoker, something Selina now thinks may have contributed to his premature death.

Our meeting comes just over a week after the publication of the Daily Mail interview with the late actor Richard Briers, in which he spoke of the lifelong cigarette habit that eventually killed him.

When I ask Selina if Simon’s own nicotine addiction was a factor in his illness, she says, ‘I’m not a doctor, but Simon smoked forever – and I’m sure it had an impact.
‘He left a big gap, especially for my mum, since my dad had already died. Yet I feel incredibly privileged that almost every week somebody who worked with Simon mentions him to me, so he’s alive in our hearts all the time.’
Three years Simon’s junior, Selina has carried on the family showbusiness tradition that began with their grandmother, Jean Cadell, who in 1935 starred opposite WC Fields as Mrs Micawber in MGM’s David Copperfield.

Selina’s father John was a theatrical agent, and Simon was always keen to act. Yet Selina, now 59, initially rejected her destiny.

Simon with Ruth Madoc in Hi-de-Hi!

‘From birth, Simon was declaring he wanted to be an actor – and I resisted joining him at first, because it felt like I didn’t exist in my own right. But I couldn’t avoid it and eventually gave in,’ she laughs.
Like her mentor brother, she’s equally adept at straight drama, taking the title role in BBC1’s glossy new 90-minute mystery adventure The Lady Vanishes.

Rather than a remake of Hitchcock’s film, it’s an adaptation of 1936 novel The Wheel Spins, upon which Hitch based his story. Selina plays the key role of tweedy spinster-with-a-secret Miss Froy, who disappears after befriending socialite Iris Carr (Tuppence Middleton) on a train.

The character was played by Dame May Whitty in the film. ‘Dame May gave an iconic performance, and of course people will make comparisons, but our version of the story is very different,’ Selina points out.
And she is up to the challenge. By right of talent alone, she ought to be as big a name as her brother, yet Selina has eschewed stardom to achieve a better work-life balance.

Three months before he died, Simon admitted his illness had forced him to readjust the pace of his ‘workaholic’ life. In an interview he likened his profession to a ‘rat-race’ which required tunnel-vision in order to succeed.
But mother-of-two Selina, who combines acting with drama teaching, says she’s never felt the pressure to push herself. ‘Show business is a very cruel world if you give yourself up to it. I don’t have goals like, “I must be famous”, because I have another life alongside acting – my teaching and my family. I love my family, they’re absolutely key to my life.’

Her marriage to fellow actor Michael Thomas has produced two children: budding actors Edwin, 25, who’s appeared in ITV’s Lewis, and Letty, 20, who is acting in student plays. Clearly proud, Selina nevertheless worries about the pitfalls for young performers.

‘I saw the Denzel Washington film Flight recently, and there was a beautiful girl naked in the opening scene. I bet Denzel wouldn’t appear naked. It makes me furious that the women are nude, yet the men are covered up. It’s never been a problem for me though, I have to say,’ she smiles.

‘Show business is a very cruel world if you give yourself up to it. I don’t have goals like, “I must be famous”, because I have another life alongside acting – my teaching and my family. I love my family, they’re absolutely key to my life'

She’s adamant her career has lasted because she wasn’t conventionally pretty. ‘Quite often the young beauties get cast for ten years then have to prove themselves in a different way. My drama teachers told me I wouldn’t get work until I was 40.

'They were wrong – I got good parts pretty quickly – but it’s a hard thing to hear when you’re young, because you want to be the beautiful girl, don’t you?’ There was a time, she admits, when she told her agent she felt stuck in ‘drab lesbian’ roles. ‘I don’t want to be limited in what I play. And I’ve succeeded, because now I either play very down-to-earth parts or very eccentric parts.’
Which is why she so admires the varied career of Sigourney Weaver. The two have been friends for four decades, since Sigourney came to London to stay with one of Selina’s friends.
‘We’re very, very close; I adore her,’ declares Selina. ‘She hasn’t allowed herself to be stereotyped.’ They even coach each other, most recently for the 2006 film Snow Cake, in which they both appeared. ‘If you get to be very well-known like Sigourney, directors don’t direct you very much. So it’s useful to have someone you trust to bat things around a bit with.’
But that proximity to such an A-lister has convinced Selina she’s happier away from the spotlight. ‘Stars don’t have any privacy. Simon was so recognisable with that lop-sided smile that people would yell out “Hi-de-Hi!” wherever he went.’
Sadly for his lookalike little sister, the actor’s no longer there to respond with his customary good-natured ‘Ho-de-Ho!’