The life of actress and amateur philosopher Joanna Lumley is like those dramatic conversations you half-hear from the next table in a restaurant – considerably less fascinating, and slightly disappointing, when you give them your full attention. Lumley’s doings have covered many inches of salacious newsprint, and now her autobiography promises to tell all. We are agog. Who, for instance, is the father of her son Jamie? For the past twenty years, Lumley has maintained an intriguing silence, fuelling speculation that she had done something she shouldn’t with a Very Important Person. Film star? Aristocrat? Does the boy even have, perhaps, the sloping forehead and piscine mien of a certain Hanoverian family? Well, you won’t learn that in these bright, chatty pages. ‘The name remains a secret,’ says Lumley. ‘It’s like one of Aesop’s Fables with an impenetrable moral.’

However, Stare Back And Smile does clear up some other cloudy points. Since she took part in a mock Common Entrance exam for a Sunday Newspaper, and passed miles ahead of several erudite males, Joanna Lumley has also had a reputation as an Intellectual. This book reveals the mind of a hearty, good-natured schoolgirl with a memory for dates, like John Betjeman’s Ideal Prefect, ‘thrillingly kind and stern’. La Rochefoucauld and Pascal need not feel threatened by the quality of her pensées, which ornament the crises in her life: ‘When things seem a bit churned up, I often think of the nature of a dog, and try to emulate his enthusiasm, forgiving nature and loyalty.’

Joanna Lumley was born in Kashmir, into an upper-middle class Army family. After a childhood divided between exotic corners of the dying British Empire and cosy boarding schools in the Home Counties, she hit Swinging London in the fabled 1960s, and proceeded to swing with a vengeance – photographic model, young thing about town, and finally actress. Famous names put their heads round the door: Lichfield, Terence Stamp, David Bailey.

The breaks came slowly. ‘Coronation Street! But how? I would be Elaine, the daughter of the headmaster of the school where Ken Barlow taught.’ Then it happened: fame and fortune, as Purdey, in that ludicrous piece of seventies tat, ‘The New Avengers’ . ‘I had taken pains to present Purdey as a keen, no-nonsense head girl of a secret agent, with easy-to-keep-hair and no real boyfriends.’

And that is an exact description of the Joanna Lumley who emerges here. She seems to be a very nice woman; a tweedy, damson-bottling, dog-loving matron, contained by mistake in a glamorous body and Jean Muir dress. It is even possible to forgive her for being on the Booker Committee which awarded the prize to Keri Hulme (whom?). In fact, she emerges from this incident without a stain on her character: she registered a written vote against The Bone People, which was ignored by her fellow judges. ‘The so-called bitchy world of acting was a Brownie’s tea-party compared with the piranha-infested waters of publishing.’ Know what she did then? She parcelled up all those free books, flogged them, and sent the money to charity. So take that, you piranhas.