The Royal Mail opted for angels on its Christmas stamps this year, commissioning the Rev Irene von Treskow, an Anglican woman priest and former art director of Saatchi and Saatchi, to design a series of stamps with angels gazing down and bathed in light. "Angels have an enduring popularity. They never really fade in people's affection," said a spokesman.
Emma Heathcote, a post-graduate student in Birmingham University's theology department, is currently researching "angel experiences". She has received 150 testimonies from people who believe they have been in contact with an angel. Most are from Christians, but she has also heard from members of other religions.
Ms Heathcote says her research supports the theory that belief in angels is growing, particularly among the young. "One explanation is that my generation is growing up without a faith. The belief in angels is a manifestation that our minds need something deeper to think about, something spiritual."
In most religions and mythologies, angels are reassuring presences, bringing comfort and the promise of eternal life. The Bible mainly depicts their innocent side - with the notable exception, of course, of the fallen archangel Lucifer. Islam teaches that everyone has two angels, one to record the sins and the other the virtues. At death the two accounts are measured against each other.
According to David Lawson, a spiritual healer and broadcaster, angels are not just a clever piece of marketing: they actually exist. He believes everyone has a guardian angel assigned to them and has written a book, A Company of Angels, published this autumn, encouraging people to get in touch with their celestial allies.
"They always appear to people in a way that is not alarming but they are most likely to materialise at a time of heightened experiences such as car accidents, trauma or illness and are at that time a very tangible presence," he said.
"People are finding a whole new spiritual direction and whatever your religion, or even if you are an atheist, connecting with your angels is a more personal spiritual route some people are beginning to explore."
Mr Lawson, 34, added: "I think angels have always been there but people are better able at this particular time to perceive them for themselves. As we get to the end of the Millennium more and more people are less directed by formal, structured religion. The idea that each of us has a guardian angel or a group of guardian angels is attractive."
According to the distinguished Yale professor Harold Bloom, America is undergoing an epidemic of "angelism". In his book Omens of the Millennium, he cited polls which show that 69 per cent of Americans believe in angels and 46 per cent believe they have their own guardian angel.
Everyone expected angels to be a fad of which Americans would tire. But instead "they have continued to grow as a commercial item beyond anyone's expectations", he said. Now Britain appears to be following suit, with the National Gallery shop stocking rucksacks with angel wings on the back and Peter Stringfellow choosing "Cabaret of Angels" as the theme for his Christmas party this year.
Films have a history of playing the angel card, from the recently re- released 1946 film It's A Wonderful Life, when the trainee angel Clarence Oddbody comes down to earth to persuade a suicidal James Stewart that life is worth living, through Wim Wender's Wings of Desire, right up to this year's City of Angels in which Nicolas Cage plays the part of Seth.