Older people who have regular sex have better physical and mental health than their chaste counterparts.

Research soon to be published will confirm that regular sex is closely linked with wellbeing among the over-fifties. It will also suggest that older women remain much keener on sex than their male counterparts.

'Self-esteem is better among older people who have sex,' said Dr Merryn Gott of Sheffield University, who carried out the study. 'Body image is better, emotional wellbeing is greater and a feeling of togetherness exists which can be absent in others.'

Zelda Curtis, a 78-year-old widow from north London, said: 'I'm delighted to say I still have an active sex life. Sex is better than when I was young because I've lost my inhibitions. I have Parkinson's disease but it doesn't stop me having sex.

'Sometimes within a marriage you build up a particular way of living because of the children. It's good to be free of that and free to start all over again,' said Mrs Curtis, who has a man friend of the same age.

'You may find it slightly more difficult to have an orgasm, but there are ways and means of dealing with that.'

Muriel, a 52-year-old quoted in the study, said: 'Sex makes you feel as though you are still wanted and attractive. You know although you're a bit fat and flabby and everything, your husband or your partner has probably known you a long time and can remember when you were 18 and 19. You still see each other as when you were younger. You can think back to what it used to be like.'

Preliminary details of the research - into married couples with an average age of 67 - were released at a meeting of the British Society of Gerontology. Most participants felt 'sexual relationships make a valuable contribution to quality of life' and considered it 'important that sexual needs are fulfilled'.

Over-seventies see some diminution in sexual activity. 'We are all a bit craggy and you've all got something that's wrong physically - aches, pains, rheumatism,' said 74-year-old John.

But it was only male participants who felt the importance placed on sex decreased with age. The finding appears to confirm the 'Joan Collins syndrome', a belief that women stay interested in sex for longer than men.

'The older you get, the more it comes down to basically just enjoying yourself,' said Jane, 74.

'Without strings attached to it, it's back down to as and when you want. When you have taken away procreation, sex is just enjoyment.'

Other benefits of regular sexual activity identified were 'a feeling of togetherness', 'sharing intimacy' and 'easing tension within a relationship'.

Medical researchers have established that women may derive more pleasure from sex as they grow older because they no longer have anxieties about contraception. However, health experts have identified unprotected sex in older people as a cause for concern.

The number of HIV cases in the United States is rising among the over-fifties at twice the rate found in younger people, according to the Centre for Disease Control in Atlanta.

In Britain, the Department of Health confirms that, while cases of gonorrhea and syphilis have risen by 55 per cent in the past five years, among the over-65s they have increased threefold.

Tessa Harding of Help the Aged said: 'The sex life of the elderly is still a subject people do not want to talk about. It's high time we stopped thinking that older people are somehow different from everybody else. Emotional needs don't just disappear on your sixtieth birthday, so who's to say the desire for physical intimacy does?'

'The only thing that sometimes does put me off is that children never really grow up and leave home,' said Mrs Curtis.

'They and the grandchildren come and stay and that does interfere with my sex life. But at the end of the day we are all sexual beings - right up until rigor mortis sets in.'
ben.summerskill@observer.co.uk