Here is a cold, hard fact: about 800,000 people in the UK are lonely. Or, put another way, anywhere between five and 16 per cent of those aged over 65 say they are lonely all or most of the time.
Loneliness is endemic and, as Jeremy Hunt, the health secretary, once said, an indictment on our society.
They believe you can create loneliness maps. This is taking data already available to councils such as the age of their citizens, those who lives by themselves, or are in a low income area or do not own a car.
This can be superimposed on a real map and could be used by local authorities and charities to provide services or find those who are not yet lonely but at risk.
And there is a desperate need for it because loneliness and isolation can be bad for a person. Some research says it can be as bad as smoking 15 cigarettes a day, or as harmful as obesity. It can cause depression and increase the risk of dementia if it is chronic enough.
It is hard to tackle, though. Through Silver Line I met Bob Lowe. His beloved wife Kath died four years ago after 65 years of marriage.
He is an ambassador for the charity – a telephone helpline – and he volunteers locally. He has family and friends. But he is lonely.
He misses his wife so much. He describes it as a pain in the heart that can hit at any time. The moments that he draws the curtains, or closes the front door, or sits down to eat are the worst.
He told me that he knows he can pick up the phone and call the family but it is no substitute.
There is a generational point here, too. Like many of his generation, Mr Lowe says he doesn’t want to bother his family – to be a burden.
But a lot of the loneliness, too, is mixed in with the grief he still feels.
He misses her touch, her smell. Over Easter, he wandered into the garden and suddenly had a waft of hyacinths. – the hyacinths she had planted.
“I lent against the wall of the house,” he told me, “and I wept.”