Last updated at 23:38 20 October 2006

"Well I’m not surprised," said the voice on the end of the line when informed yesterday that Professor Stephen Hawking is divorcing his wife Elaine.

"Not surprised at all - I just wish it had happened a long, long time ago."

The voice belonged to a nurse who used to care for Prof Hawking; she parted company with him, reluctantly, after Elaine became the second Mrs Hawking in 1995.

"She is the reason I left. It’s the reason everyone leaves. It’s impossible to reconcile the way she treated Stephen with the ethics of our profession. I don’t want to say anymore because it brings back painful memories."

It is a sentiment shared by almost all Prof Hawking’s friends and family; relief that he is now finally free of Elaine, and distress that it has taken so long; the couple have been together for 17 years.

It is a relationship that, almost from the beginning, has provoked a storm of controversy - and suspicion - the wheelchair-bound Prof Hawking, 64, who has suffered from motor neurone disease since the age of 22, and the "controlling, manipulative and bullying" (the words of another former employee) Elaine.

Because for years there have been shocking rumours of violence and abuse against the vulnerable scientist - mental as well as physical - supported by his own children no less.

There is unlikely to be any reference to these allegations in divorce papers lodged by both parties at Cambridge County Court, however.

Prof Hawking has publicly denied such claims in the past. For a fiercely proud man who, though feted as possibly the world’s most famous living scientist, must rely on others to help him perform basic human functions, it surely would have been the final indignity: to be forced to deny that he is a battered husband.

Next month, he will receive the Royal Society’s most prestigious prize - the Copley Medal - won by such luminaries as Charles Darwin, Benjamin Franklin and Albert Einstein.

Conspicuous by her absence at the ceremony, of course, will be Mrs Hawking, 55, who is thought to have already moved out of the marital home.

So why after all these years have they split up?

There have been suggestions that he has found a new girlfriend but a source close to the family has strenuously denied to the Mail that the break-up was caused by Prof Hawking having an affair.

"It is complete and utter rubbish," he said.

What's more, it is also rumoured that Mrs Hawking has become "close" to another man, a former carer, believed to have been appointed by Elaine, who used to look after her husband.

"I met 'him' once," said someone who worked for Prof Hawking.

"It was a few years ago before they supposedly became involved and I can't really remember anything about him."

Mrs Hawking - or Elaine Mason, as she was formerly known - was also married when she joined Prof Hawking’s nursing team back in the Eighties; she subsequently left her husband of 15 years, leaving him to bring up their two young sons.

But what of her now? She will leave her second marriage considerably wealthier than she did her first.

The couple’s townhouse in Cambridge, purchased in 1992 and now worth £750,000, is in their joint names.

Moreover, he has amassed a vast personal fortune.

More than 210,000 copies of his book A Brief History Of Time have been sold in the past eight years alone, netting more than £2 million. He has also made lucrative sums from other books.

On Thursday, Mrs Hawking, who has always denied marrying for money, cycled to the (former) marital home where she was understood to have attended a meeting with solicitors.

"I have been told that - surprise - one of the stumbling blocks in the divorce is money," said an old family friend.

Under different circumstances, this would be hardly worth mentioning. But, in the light of all the other allegations, it is, you might think, particularly telling.

Today, as the details of their divorce are thrashed out by solicitors, those who know Prof Hawking provide a chilling insight into his private life over the past decade.

In 2000, detectives launched an inquiry after Prof Hawking made a number of visits to Addenbrooke’s Hospital, Cambridge, suffering from cuts and bruises, and another inquiry was opened in 2003 after his daughter Lucy rang police.

Prof Hawking declined to explain how his injuries had come about. A number of his former nurses, however, were in no doubt.

They alleged that over the years his wife inflicted a catalogue of injuries on the vulnerable scientist: fractured his wrist by slamming it on to his wheelchair; humiliated him by refusing him access to a urine bottle, leaving him to wet himself; gashed his cheek with a razor, allowed him to slip beneath the water while in the bath, ensuring water entered the tracheotomy site in his throat; and left him alone in his garden during the hottest day of the year so long that he suffered heatstroke and severe sunburn.

It is these allegations that police investigated.

But a woman who worked for him at Cambridge University says the "unexplained injuries" began "many years before" the police became involved.

"He used to regularly come in with bruises and cuts," said the source.

"I remember once he turned up with a black eye. I asked him; 'How did that happen Stephen?' He replied: 'I bumped into a door.' That was obviously my cue to shut up, so I did."

"It was common knowledge that Stephen was very, very unhappy long before all the allegations appeared in the papers."

"Before they were married they went on holiday to Israel and we heard later that they had a furious row and their hotel room was damaged [former nurses claimed that Elaine would 'throw things around the kitchen' during tantrums]."

"I remember asking Stephen why he and Elaine stayed together and he said: 'any relationship was better than none'."

"In the end I left Stephen because I couldn’t stand it. I felt very strongly that I could no longer carry on without feeling that I was colluding in what was happening."

"The police interviewed me a few years ago as part of their investigation."

Elaine, once described as a 'churchgoing mother of two' was, perhaps unsurprisingly, never particularly popular with the Hawking family - primarily his first wife Jane, the mother of his three children, Robert, 39, a software engineer, Lucy, 36, a journalist, and Timothy, 27.

Elaine was, as we know, originally Prof Hawking’s nurse and joined the staff after he had a tracheotomy operation in 1985 - the result of a previous pneumonia infection which nearly killed him.

The operation left him unable to breath unaided and in need of round-the-clock supervision.

It was Elaine’s former husband, engineer David Mason, who made the voicebox which created the robot-like vocal tone for which Prof Hawking is now famous.

From the start, say friends, she set out to ingratiate herself with him, and, over a period of time, the family noticed the mesmeric hold the 'new nurse' was beginning to exert over her charge, and felt deeply uneasy.

"She brainwashed him to think that she was the only person who could possibly look after him," one friend recalled.

"She was also really jealous of his children and the close relationship they had with him."

Matters were complicated when his wife of 26 years began having an affair in the Eighties - with, apparently, Hawking’s tacit approval - with a choirmaster, whom she had befriended after his wife died of leukaemia.

Elaine began accompanying Prof Hawking on trips abroad.

Prof Hawking and Jane divorced in 1990.

He finally married Elaine in 1995 but neither Jane or their three children attended.

"I think he has been very ill-advised," his former wife said at the time.

But how could she - how could anyone - predict the events that followed?

First, say sources, Elaine began dispensing with the nurses who cared for her husband and replacing them with carers.

They were cheaper certainly, but that, according to those who knew the family, was not the point.

"It was much more about control," one long-standing family friend told the Mail.

"Elaine was a nurse herself, although she had allowed her registration to lapse."

But she didn’t just want to be on the same level as those who looked after her husband. It was very important to her that she was superior to them which is why she began employing less qualified staff."

Another former member of Prof Hawking's "care team" added: "Anyone who has ever cared for someone who is elderly or disabled would understand how difficult it is, but, on the other hand, I was worried about his well-being which is why I eventually left."

"I just couldn’t stand by and watch him being hurt."

"Why, then, if this is indeed true, did Prof Hawking cover up for his wife?"

"Someone with Stephen’s brilliance must, inevitably also possess an element of arrogance," said a friend.

"Stephen has always striven against the odds - both physically and intellectually."

"When he makes a decision he becomes single-minded about it, about convincing the world of its validity. And so, I feel, it is with Elaine: having made his bed - against much advice - I believe he felt he must lie in it without complaint."

"For a man like Prof Hawking to admit that he made a big, big mistake would be the ultimate humiliation."

There would also have been the humiliation, in his eyes at least, that his vulnerability left him unable to defend himself even against his wife.

For that, it seems, Prof Stephen Hawking has paid a terrible price.

Normally, the break-up of a marriage is the cause of immense sadness and regret. But today, the family and friends of Prof Stephen Hawking - indeed for everyone who knows and admires him - those emotions have been replaced by a profound sense of relief.