I would not normally waste praise on something as unambitious as Doc Martin, but watching Merlin and Trinity make me appreciate how right ITV gets its gentle, Sunday-night ratings banker. Martin Clunes, who plays Martin, the grumpy, haemophobic surgeon turned Cornwall GP, is no great actor but no one does a volcano on the permanent brink of eruption better. Last night, as ever, his equilibrium was sorely tried: by a dog that wanted to be his friend, a deaf rig worker who spoke only at high decibel (cue, doubtless, complaints from Stephanie Beacham), and a smug old flame who misdiagnosed a condition. But we wanted to know what had happened to Louisa, didn't we? His almost bride turned up, just before the end credits. And she's pregnant. I'm sure the doctor will cope with that fine.

Doc Martin (ITV1, Sunday), back for a long-awaited fourth series last night, stars Martin Clunes as a surgeon who is forced to take up a new career as a GP in a Cornish fishing village after he develops hemophobia, a fear of blood so extreme that he turns grey and throws up at the mere sight of the stuff. Funnily enough, I have the same problem with Mr Clunes, and since he's never off our screens for more than a day or two you can imagine the dire implications for my career as a telly critic. He's annoyed me ever since Men Behaving Badly, there was that awful documentary where he slobbered all over dogs, but the last straw was the catastrophic remake of Reggie Perrin.

Still, Dr Martin Ellingham is working very hard to overcome his syndrome, and so am I. Doc Martin is the right place to start because it's pretty damn good: not for nothing did the finale to the third series notch up 10 million viewers. The scripts have a slight tang of nastiness about them - too slight for my tastes, but just occasionally its mockery of the Cornish locals reminds me of the take-no-prisoners humour of Nighty Night. The malevolence mostly emanates from the Clunes character, who is grumpy and sarcastic: that's a blessed relief, because it means that the actor rarely gets to twist his face into the rubbery aw-shucks grin that gets my phobia going.

Anyway, last night's plot revolved around a woman who was wrongly diagnosed with a cyst in her stomach: it turned out to be a diverticular mass. Also, there was a subplot involving the village restaurant owner, played by an actor so grotesquely fat that you felt it was irresponsible of the producers to put him on screen rather than send him off to a real doctor. I'm sure that those impressive layers of lard help him get parts, but is it worth it?

Martin Clunes has put on a few pounds, too - rather disconcertingly so, if you happen to be the same age as him, because it reminds you that the late-20s layabout of Men Behaving Badly is now properly middle-aged. I'm afraid I became rather distracted by his weight in this episode. Why does he always wear three-button suits in his dramas? Doesn't he realise how unflattering they are to the fuller figure? And I sniggered when Ellingham's aunt Joan (Stephanie Cole at her doughty best) dropped off an enormous fruit pie at his surgery. He was supposed to be irritated by the interruption, but it did look delicious and Clunes's eyes lingered a bit too long on the pastry. I shouldn't think he needed much persuasion when the director yelled, "Cut!"

Clunes brands STV's drama opt outs "churlish"

Martin Clunes has criticised STV's decision not to show the fourth series of Doc Martin on its network, labelling the move as "churlish".

Another dollop of Sunday night whimsy as the hemophobic former surgeon (Martin Clunes) and his cluster of eccentric Cornish folk return for a fourth series. Life continues much the same in the tiny fishing village of Portwenn, with all the locals getting ever more odd. The aging local chemist Mrs Tishell (Selina Cadell) has developed nymphomaniac tendencies. Scatter-brained receptionist Pauline (Katherine Parkinson) is losing sleep because of her brother's snoring. Big Bert Large (Ian McNiece) is missing the spark of love in his life. And all of them, for some reason, think they'll get some sympathy from the world's least considerate GP. The truculent medic, meanwhile, is nursing his own wounds following the departure of his paramour, Louisa, and it's made him restless. When he hears a desirable consultant's post is opening in London, he thinks that finally he might be able to overcome the fear of blood that previously ruined his career. First though, he has to overcome the shock of meeting a snooty former fellow student at the hospital in Truro, surgeon Edith Montgomery (Lia Williams), who makes no bones whatsoever about letting him know how low she thinks he's fallen.

Almost every one of this show's nine million viewers shed a frustrated tear at the end of the last series when, at the 11th hour, the irascible GP didn't marry local school headmistress Louisa after all. But has it made him happy? Has it heck. He's more bad-tempered than ever and, despite the haemophobia that sent him scurrying from his surgeon's position to take up a post in the sleepy Cornish village of Portwenn, he plans to return to the big city and the operating theatre. Well, it probably beats treating a succession of tiresome patients and judging the annual which-pig-looks-most-like-its-owner competition.

A chance meeting with an old girlfriend from medical school days, who's now a high-flying private doctor, only stiffens his resolve even more. Martin Clunes screws up his face into ever-grumpier expressions and does a terrific job of being curmudgeonly yet lovable, while most of the cast of amiably eccentric characters stays just the right side of cliche. As for Port Isaac, where the series is filmed, it looks simply enchanting. What's not to like?

For supposedly benign, ratings-friendly Sunday night fodder, the first episode of the fourth series of Doc Martin has a rather gory opening. Martin Clunes, reprising the role of Martin Ellingham, the GP with the bedside manner that makes Alan Sugar look like Florence Nightingale, is seen running down the high street carrying a bag of bloody liver. Then, an angelic blonde girl has a pencil embedded in her face. And to cap it all off, the Doc ends up with a shard of glass embedded in his palm. All these signs are pointers to the main storyline - Martin is considering going back to being a surgeon but must first conquer the fear of blood that scuppered his original career choice. His reason for the change of heart? The absence of a certain school teacher...

Video: Martin Clunes Interview

After a break of almost two years, comfy comedy drama Doc Martin makes a welcome return to the ITV schedules this weekend for its fourth series. We sat down with Martin Clunes for a wee chinwag to find out more.

ITV must be cock-a-hoop to see one of their sure-fire ratings bankers return for a new series of eight episodes. Martin Clunes is back as irascible and blood-fearing GP Martin Ellingham, tending to the ills of the populace of Cornish fishing village Portwenn. At the end of the last series, fans were aghast when the wedding of Ellingham and his on-off love Louisa (the fabulous Caroline Katz) didn't go ahead. Louisa is still around, but our favourite GP bumping into an old flame from medical school isn't going to make things any easier. Good, honest fun.

What Buckham Fair means to Martin Clunes

A man as much in the public eye and with as big a heart as Martin Clunes is bound to get swamped with requests to help good causes, but he's a man who hates to say no.

What started in a humble way as a small horse and dog show last year on his 20-acre homestead in Beaminster has grown to a fully-fledged fair and a way of saying a big yes to local charities.

Doc Martin - Series Two

Doc Martin is the kind of show that builds up steam very slowly; there's nothing flashy to grab viewers by the neck and make them want to orgy on it like many high-concept shows. But, gradually, it works its magic and its characters ingratiate themselves in these slight but sweet stories.