"I think especially if children are ill or obviously upset, then there is no point trying to confine them to their own beds," says Natasha, 32, a schoolteacher. "We try to avoid him coming in at one or two in the morning, unless we are in a strange place, or he is ill. But if he wakes up after about five in the morning, then we know now that the only way we will get another hour's sleep is by having him in bed with us."
The Chamberlains' relaxed attitude to sharing the hitherto sacrosanct marital bed with the children has recently become fashionable again. For the last 100 years or so, allowing a child into the parental bed was thought to be the quickest way of spoiling the child.
Bed-sharing or co-sleeping is one reason why the size of a British double bed is increasing. While sales of "standard" doubles, at 4ft 6in, have fallen, sales of "King-size" 5ft and even 6ft beds have increased in the last five years, according to figures from the Sleep Council. Warren Evans, who has been making beds for 20 years at his workshop in north London, says: "Twenty years ago I would sell about 10 6ft beds a year. Now it's two a week, always to couples with children."
"Sleeping apart is in fact a relatively new and limited development in human evolution, dating from about the turn of the 19th century," says Dr David Haslam, author of the book Sleepless Children. "On a global scale, more mothers sleep with their children worldwide than they do with their partners. It is only in a tiny corner of the Western hemisphere that separate bedrooms are the rule.
"Today, in the West, more and more parents are returning to the idea of having their babies in bed with them; other countries have avoided this trauma by following this age-old tradition throughout."
James and Jo Murphy, parents of six-year-old Jack, adopted the "traditional" approach when Jack was only a few weeks old. While James, who needed to get to work in the morning, slept in splendid isolation, Jo and and baby Jack shared the same bed until, aged three-and-a-half, Jack went into his own bedroom at his own insistence. Jack still comes into his mother's bed from time to time. "Jack was a sleepless baby and the idea of leaving him to cry it out appalled me," says Jo. "It is terribly unnatural forcing your tiny offspring to sleep on their own. Having said that, Jack didn't sleep fully through the night until he was two, but at least I didn't have to get out of bed to deal with him."
Disturbed nights caused by sleepless young is becoming an increasing problem today says Mary Daly, professional officer of the Health Visitors Association. "Whether children's sleep has actually deteriorated, or whether sleep has become more of an issue in households where both parents work, we just don't know. But what we do know is that sleep and lack of it is a much bigger source of complaint than it used to be." Hence the nationwide network of GP Surgery-based sleep clinics, which has sprung up in the last few years, advising thousands of bleary-eyed parents how to get their child to sleep well through the night.
Although parents are not advised to take a very young baby into bed with them, because of the slightly increased risk of cot death in babies under six months who sleep with their parents, health visitors now do not advise against bed-sharing with older infants and toddlers. This was not the case in the Sixties, when health visitors would accuse mothers of spoiling their children if they took them into bed with them.
Fortunately today, many parents are far more easy-going about their young children's night-time routines, says Sheila Kitzinger, an anthropologist.
"One of the most valuable things you can give children is self-confidence, bringing them up to feel safe, secure and loved. Who can be safer than a child cuddling the warm, enveloping arms of her mother?"
She says that the trend towards separate beds in the last century was, as most social changes usually are, the result of the middle classes aping the upper classes, and the working classes, when space permitted, aping the middle classes.
The two main fears parents have today about bed-sharing are a lack of opportunity for intimate, child-free moments and a fear that the child will never want to sleep in his own bed again.
"Both these fears are unfounded," says Dr Haslam. "These days, most children are put to bed in their own rooms and only come into their parents' bed when they wake up. The most common time is after two or three in the morning, when lovemaking has been concluded. And by the time the child is three or four, it is very often the child who makes the move away from the parental bed."
He stresses that parents who want to keep to separate rooms should not feel pressured into bed-sharing: "I only advocate bed-sharing when both parents are happy with it," he says.
Natasha Chamberlain adds that ideally, young Thomas would sleep through the night peacefully in his own bed. "The trouble with toddlers is that they do wriggle so," she says.Reuse content