"The viruses which cause colds are always around," he adds, "and children get more colds than adults because their immune systems are still developing recognition of these bugs. But that still doesn't explain why some people seem to catch colds more than others." The answer, he believes, has nothing to do with external attack but internal defence: you have failed to maintain an efficient immune system.
Apart from developing a healthy way of life (getting fit, eating a well-balanced diet, stopping smoking, coping with stress and taking a positive approach to life), Newell suggests three specific anti-cold strategies.
The first involves exposure to full-spectrum light. Newell cites a 12- year US study of 4,000 male students at Cornell University, which showed that when chronic cold sufferers were given thirty minutes a week exposure to ultra-violet light the number of colds was almost halved. Newell advocates "healthy" tanning for children and adults with, of course, a caution to avoid over-exposure. He suggests exposing the body to sunlight at least once a year, but preferably through the summer months, to the point where levels of the pigment melanin are activated strongly. "By programming your body and manufacturing ... vitamin D from cholesterol circulating in the bloodstream, the sun not only keys up and maximises immunity, but acts to prevent diseases," he says. "The trick is to activate melanin levels at a young age and maintain that protection for life."
Second, he recommends a daily glass of fresh orange juice to maintain the body's levels of vitamin A, C and E. "This, interacting with the effects of the sun and the production of vitamin D, is sufficient to maximise the protection needed by a healthy person."
Third, he advises against the use of over-the-counter medicines to relieve cold symptoms such as a sore throat or fever, and - unless essential to treat a secondary infection - antibiotics. "A sore throat ... is an indication that the body is doing the job it was designed to do ... if you start swallowing aspirin or paracetamol at this stage, all you will do is slow down the process and inhibit the immune response."
Newell is also convinced that whether you develop a cold depends on your initial response to symptoms. If you panic at the first sneeze and think "I can't get a cold now!", you are more likely to succumb. If, on the other hand, you think "I won't get the cold that's going round because my immune system is already on the case" you'll have a better chance of beating the bug.
So is this the answer: suntans, orange juice, no "cold cures" - and a positive mental attitude? Dr Ron Eccles of the Common Cold and Nasal Research Centre in Cardiff is not convinced. "Ultraviolet light - which is found in sunlight - does kill off viruses and that may be one reason why we get more colds in winter. There is evidence that aspirin can affect viral shedding, so taking it may mean a cold hangs around a bit longer. But one study on flu found that taking aspirin did not affect the immune response." The cold, he adds, "is a herd disease. The only sure way to avoid catching one would be total isolation from other human beings."