I always love speaking to the University of the Third Age. The audience consists of bright, adventurous old people, who always arrive early. Unusually for the British, they fill up the room from the front row. And instead of looking grumpy or impatient, they sit there smiling waiting for me to begin. It's tempting to believe that these are the lucky, happy older people, the ones who never feel lonely.

So I was shocked when, at one U3A meeting recently, a lady told the rest of the audience, "We may not want to admit it, but everybody in this room knows from personal experience what it's like to feel lonely." And there was a murmur of agreement.

It took great courage for that lady to confess and confront the reluctance in many older people to admit that they feel lonely, reluctance which comes, I believe, partly from pride, and partly from a desire not to become a burden. They won't even admit it to their own families.

As Beryl wrote to me, when her husband died: "I didn't want to tell my family and friends how I feel. It's my pain, and I don't want to distress them". So she rang The Silver Line Helpline, the new charity I launched a year ago, "and I found myself pouring my heart out over the phone to a lovely woman. That night, for the first time since my husband died, I had a good night's sleep."

The Silver Line is a 24-hour free helpline for older people, (0800 4 70 80 90) which offers friendship and advice.

Feeling lonely can destroy self-esteem

It receives around 1,000 calls a day, most after 5:30pm, through the night and over the weekend when there is nobody else to talk to. And the vast majority of calls are about loneliness.

In addition to the helpline, we offer regular calls from Silver Line Friends (trained volunteers who donate an hour a week, and work from home).

We urgently need more volunteers, which is ideal work for older people who may themselves have experienced loneliness, enjoy sharing memories and life experience, and will be rewarded by the knowledge that they have made a real difference.

As John told us, isolated and in his 80s: "When I put the phone down, I feel like I've joined the human race." At that memorable meeting of U3A, most in the audience were mobile and active, regularly attending meetings and classes.

But that didn't mean they had been spared the pangs of loneliness. Indeed, one definition of loneliness is "to have plenty of people to do something with, but nobody to do nothing with."

I have quite a busy life, but all the same I have admitted publicly that I felt the numbness, the bleak vacuum of loneliness when I moved from my family home into a flat, and found myself living alone for the first time at the age of 71.

When I wrote about it, one close friend rebuked me for having revealed so much. "How could you write like that," he asked me. "Haven't you got any pride?" There is a stigma attached to loneliness, as if it's an admission of failure.

And there are, I suppose, people who are perfectly happy on their own. I envy them. For myself, happiness is about sharing.

And I desperately miss the person closest to me with whom I used to share all my most crucial experiences, happy and sad, my late husband Desmond Wilcox. Loneliness in my experience is often caused by loss: loss of a partner, of a sense like sight or hearing, the loss of mobility, even of a driving licence.

The impact of loneliness erodes confidence, and destroys self-esteem.

One lady, who had lost both her husband and her son, and who often spends three days at a time without seeing or talking to anyone, wrote to me and said: "I am an optimist by nature, and sometimes I have to be, when I am facing another pointless day when I am a waste of space. I find myself talking to the television; how sad is that? And I dread the long winter evenings, when the darkness closes around me."

It is well known and recognised that loneliness brings with it serious health problems. Why bother to eat properly, or take exercise, when you are on your own? Is life really worth living, with nobody to share it with? But, unlike other forms of depression, loneliness can be easy to cure. All it takes is company.

We Jews often congratulate ourselves on our closely knit families, our congregations and charities that look after the most vulnerable. But, even so, though we may find it difficult to admit it, if we open our eyes, and our hearts, we will find that loneliness exists in our own community.

The Jewish Chronicle's call to action asks us to reach out to isolated older people, make that phone call, that extra visit, volunteer and offer support.

It takes little time, but it can be enough to transform lives, reassure older people that they are valued, that we care about them, and that they are indeed, as John said, valued members of the human race.