Rona Dougall: Use it or lose it? Well, using it seems key to a long, happy life and old age

Lulu on the tube. Still rocking it in later life.

How old is old these days? That’s the question posed by writer Camilla Cavendish in a new book which challenges lots of perceptions about ageing.

We’re all living longer than before. In fact, by 2020 there will be more people on earth over the age of 65 than under five.

That fact poses lots of questions about how we use this extra time. In the past most folk would start to think about retiring in their 60s, but if you live until your 80s that’s a heck of a lot of free time to fill.

I interviewed legendary mountaineer Hamish MacInnes last week at his home in the beautiful village of Glencoe.

In the shadow of his beloved hills, he told me how, at 88, he was still hard at work, writing books and taking photos.

He led the Glencoe mountain rescue team until he was 61, only resigning as he had too much else to do. When I asked him if he missed being up in the mountains, he replied he didn’t as he had lots of other interests.

And that seems to be the key to flourishing in older age – having a purpose and keeping busy.

Lulu, for example, off to play the O2 arena in London last week. She not only jumps on the tube but fires off a wee cheeky tweet about no one giving the “old bird” a seat.

In her book Camilla, who once led No 10’s policy unit, explored how other societies around the world were dealing with this new, extended middle age. On the Pacific island of Okinawa there isn’t even a word for retirement. There, great-grandparents are looking after their grandchildren even when they hit their 100s.

I would ask my mum to look after my kids more, but she’s always busy. She’s nearly 80 but as vibrant as ever.

The adage use it or lose it has never had more meaning.

More and more people are returning to work in their 70s as, having given up work, they get bored rigid tending their gardens and going to the local pub.

It sounds like heaven to me, but then I can’t retire. When your long-term financial plan depends on winning the lottery, you know you’re on shaky ground.

I’m not sure how my TV bosses would feel about a pensioner reading the news, but that’s a whole other column. And that’s many, many years away anyway, I hasten to add.

Poverty in old age is a real issue for many, too. In Japan there has been a crime wave of elderly shoplifters. Basically, they’re so skint they want to be put behind bars so the state can support them.

I’m not sure that’s how I’d want to spend my dotage. The upside, I suppose, would be that you wouldn’t have to cook.

Effective anti-ageing treatments are the holy grail of the pharmaceutical industry now. And some scientists believe that by 2150 there will be a 150-year-old person.

But, as Freddie Mercury sang, “Who wants to live forever?”