Sarah Sands: Three cheers for Paula, my rhino, and chickens everywhere

By the time you read this, the professional London Marathon runners will have probably finished, the boundaries of physical excellence extended. The huddled masses could finish any time before sunset.

We know the arguments against marathon runners. Why must we celebrate a private hobby? Why do so many of them wrap a day out in charitable virtue? Online comments from non-participants are outbursts of frustration – if you want to give to charity do it, there is no need for exhibitionism as well. The darker sceptics want to remove charity altogether from running. Why should you name a charity in order to enlist?

This is to misunderstand the whole character of the race. Running is nerdy and competitive. Amateur marathon running is peaceful and benign. It is the national street party that David Cameron is trying to hijack for the royal wedding. As the runner, the late Chris Brasher put it: "It is the greatest folk festival the world has seen."

The London Marathon is as ingrained in the national character now as Comic Relief, and is a similar target of misanthropy. The "let's be serious for a minute" reverence for fine causes is awkwardly juxtaposed with larkiness. Well, there it is: either you enjoy a heartwarming Betty Blue Eyes view of humanity, or you need to avoid London today.

I have witnessed two generations of the London marathon. A long, long time ago when I was a Doris Day young wife and mother (long enough ago for historical revisionism) my husband entered the London Marathon. I had no idea what this was event was, except that mysterious and unnecessarily long training coincided with domestic chores such as nappy-changing.

One Sunday, he vanished early, finally reappearing around lunchtime like Ulysses, hobbling down the street and clutching, for some reason, a sheet of Bacofoil. What would you have done if you had been in my place? Exactly. I shoved a bawling child into his arms and chided him for being late for our walk to Richmond Park.

Nearly 20 years later, we have all undergone social reform, and some of our best friends are marathon runners. Now I listen indulgently to talk of running times and carbo-loading. I know what weekends are for. And I salute the human narrative. The cause close to my heart is the foundation of the Big Society, a kindly recognition of the lives of others.

Runners, as you pummel the streets of London, delighted that at least you have not been overtaken by the rhino, I should mention that the rhino – or one of them – is my son. He started with the ambition to be the fastest ever rhino in the Marathon, but, being young, and easily distracted, he is now looking at the title of least trained rhino. He wonders if authenticity might be enhanced by lying down in the road. Is his wife waiting at home, like that battleaxe of yesteryear, eager to pack him off on the family walk?

My daughter-in-law entered a half- marathon alongside rhino husband, to encourage him. She bathed his bleeding hands and advertised his success on her mobile camera phone. She is optimistically holding court at a local pub this afternoon to celebrate her husband's achievements.

Sneer if you wish, but I think the London Marathon is the best part of us. Ordinary people, having a go, propelled by charitable instinct. Poignant endeavour = happiness.

Sarah Sands is deputy editor of the 'London Evening Standard'