Finger of blame: David McCallum, who made his name in The Man From U.N.C.L.E suffered from Dupuytren's contracture

It was as the Mozart concert on the television was reaching a climax and actor David McCallum stood in front of the screen, accompanying the symphony orchestra on his oboe, that he realised there was a serious problem with his right hand.

'I couldn't reach all the keys,' explains McCallum, best known as the dashing Russian secret agent Illya Kuryakin in the Sixties TV drama The Man From U.N.C.L.E.

'I'm a keen musician and had been playing along to a DVD at Christmas last year,' recalls David. 'The tightening of my hand had come about slowly and was uncomfortable rather than painful.

It had reached a point where two of the fingers on my right hand were curling inwards so far towards the palm of my hand that I couldn't unfold them sufficiently to play the notes.'

David, who was born in Glasgow and now lives in New York where he stars in American crime series NCIS, realised that he could no longer ignore the condition.

He was suffering from Dupuytren's contracture, named after the 19th Century French anatomist Baron Guillaume Dupuytren, who carried out the first successful operation to alleviate the condition.

Other famous sufferers have included Lady Thatcher, Ronald Reagan, actor Bill Nighy and playwright Samuel Beckett.

Dupuytren's contracture is a benign condition but a common and progressive one. It involves the thickening and contracture of the fibrous connective tissue beneath the skin of the palm.

A clawing deformity of the fingers, particularly the little and ring fingers, develops over several years. In half of all cases, both hands will suffer and, although rare, it can affect the toes and soles of the feet.

An estimated two million people in the UK suffer from it. More than 12,000 cases are operated on here each year. Surgery can help prevent fixed deformity but recurrence is estimated in about half of all patients who have had an operation.

There are three main surgical options. The first is open fasciotomy, where the skin is opened and the thickened tissue cut; the second is a needle fasciotomy in which a needle is inserted to cut the thickened tissue.

Margaret Thatcher and Bill Nighy have also suffered from the condition

The final option is a different open fasciotomy where, once the skin is cut open, the thickened tissue is removed.

The tough tissue had been forming under David's skin, beneath the palm of his right hand, and had thickened and shortened to the point where the tendons connected to the fingers could no longer move freely.

As the condition worsened - in David's case over several years - the affected fingers had formed a partial claw.

David was also in the right age bracket for the condition - the man from U.N.C.L.E., amazingly, is 76. It can affect up to 20 per cent of men aged 60 or over and 20 per cent of women over 80.

Professor Joseph Dias, Professor of Hand & Orthopaedic Surgery at the University Hospitals of Leicester, explains: 'Dupuytren's contracture is a very peculiar disease and research into it is still ongoing.

What we do know is that it comes to people in their late 40s, 50s and 60s. Those who suffer from it have a genetic predisposition towards getting it - in nearly 70 per cent of cases, family members such as brothers and aunts may well have it, or have had it, too.

'Traditional thinking suggests it is associated with Viking genes. North Europeans whose ancestry can be traced back to the Vikings appear more likely to suffer the condition.

'There are multiple genes and chromosomes that are more common in those people who get this disease than in those who do not. But we are still not sure why those of Viking origin seem more predisposed to suffer from it than others.'

Professor Dias also says that research has shown that the disease can be triggered by particular activities. 'For example, there's far more of an occurrence of Dupuytren's among members of the Climbing Club of England than there are among groups of people who don't climb rocks.

There's a possibility that the tissue under the palms of the climbers' hands reacts more quickly to the condition than it would if the hands weren't pressing down on rocks so much.

'As for those who play music, such as David McCallum, and use their hands a great deal, it may be true that their activities also trigger the disease, though as yet there is no definitive research on the subject.'

Although David has relished roles in TV dramas from Colditz to Sapphire &Steele, he has been able to explore his interest in all things medical through his role as pathologist Doctor Donald 'Ducky' Mallard in NCIS, which he has played for the past seven years.

'I've become an expert in forensics and once I was diagnosed as suffering from Dupuytren's contracture, I set about investigating it myself,' he says.

David divorced his first wife, actress Jill Ireland, with whom he had three sons, after ten years of marriage and has been married to Katherine Carpenter since 1967. They have a son, Peter, and a daughter, Sophie.

He discovered during his research that a great many Scots suffer from the disease but, in many cases, the build-up of tissue under the skin never becomes so appreciable that the fingers curl and surgery is required.

'I suppose I was unlucky in that I did need surgery,' he says. 'However, I was able to carry on with acting without the condition of my hand seriously affecting my work or the pain distracting me.

'Music is an important part of my life and my fingers had become so bent that I feared I would never be able to play the oboe again. And I didn't want to entertain that thought.'

David consulted American orthopaedic surgeon Michelle Carlson and underwent surgery in his adopted city of New York earlier this year.

'I was put under general anaesthetic, my hand and fingers opened up and the offending tissue removed. They were then stitched back together and each finger given its own splint so that they would be encouraged to move outwardly from the hand, rather than inwardly.

'Michelle would drop by and see me as I recovered from the operation, massaging my hands, and thereby increasing the circulation of blood, during her visits. My post-op care also included several months of physiotherapy, and I discovered that Pilates was a wonderful way of bringing suppleness back to my hand.

'But nothing, during my rehabilitation, was quite so pleasant as one of Michelle's hand massages.'

While David admits he has to work hard to keep himself in shape now that he is well past pensionable age, he says he feared losing his 'lithe figure' while recovering from the operation.

'I'm afraid I regarded it as the perfect excuse not to exercise, not to get on the running machine and stay in trim,' he admits. 'It was a poor excuse. Just because I had a recovering hand didn't mean I couldn't do a little light jogging.

'It didn't help that my recuperation from the operation coincided with a trip to Europe with Katherine and a chance to sample some of the better restaurants.

'I'm afraid I reached a point of saturation where I'd simply had enough of fine dining. And, believe me, it takes an awful lot of fine dining before I feel that way.'

Since returning from his home in New York to Los Angeles, to film the new series of NCIS, David has managed to exercise three or four times a week, when the heavy filming schedule on the drama permits, attending a couple of Pilates classes every week.

He says: 'I am just grateful that I am able to take part in any kind of exercise at my age. As a child, I had a tubercular gland in my neck which weakened me and one of my earliest memories is of being wheeled around the Botanical Gardens in the west end of Glasgow in a bath chair as I recuperated.

'Even as an adult, I felt as if I were held back by my physicality. I was a small, emaciated blond with a caved chest, so there weren't an awful lot of parts for me. I guess that landing the role of Illya Kuryakin gave me confidence in myself and confidence in the way I looked.'

David took great delight, a few weeks ago, in putting on the DVD of the Mozart symphony he had been playing when he first realised his partially clawed hands could no longer reach the keys - and this time playing the oboe solo without a hitch. 'It was a wonderful feeling and a wonderful experience,' he says.

'To spend one's afternoon with your own symphony orchestra for company takes some beating.'

However, according to Professor Dias, David should brace himself for the possibility of needing more surgery. 'One of the problems with Dupuytren's contracture is that you do not sort out the cause of the disease by operating on the hand, you only relieve the problem it has caused,' says Professor Dias.

'That's because the condition is genetic and we don't yet know what triggers it. Wait long enough and there is a real chance that scar tissue will start to re-form beneath the palm - within three years it recurs in one in every six people who suffer from Dupuytren's contracture and have undergone surgery. Wait long enough, and it recurs in the majority of them.'

As for David he is decidedly upbeat about the long-term prognosis.

'To still be making a living as an actor, more than 40 years after U.N.C.L.E., proves that medical problems in one's early life, and even difficulties in that direction in later life, too, are no bar to working regularly.'

NCIS returns in a new series on Five on Wednesday, January 6, and runs for 26 weeks.