BAGS are a girl's best friend, allowing women to keep their must-have possessions close at hand. Whether it's their mobile phone, diary, snaps of their children, a favourite lipstick or a pair of tights, handbags let women face the world safe in the knowledge they can rescue themselves from a bad day with a quick makeover or a call to a loved one - with no worries about laddered tights.

I never leave home without my favourite bag - a small black bowling bag - crammed to bursting point with the essential and the eccentric.

There's the obligatory brolly, my contacts book, purse, at least three lipsticks, numerous pens and pen tops, a chequebook, hair clasps, sunglasses, prescription glasses and old press releases about jobs I covered weeks ago, plus an apple, banana and a packet of oat cakes.

Analysis of these contents tells you a lot about me, not least that I'm a journalist, who likes to wear lipstick and munch on healthy snacks.

But it's not only the contents of a woman's handbag which tells us about her - the actual bag can speak volumes too.

My pvc bag shows I've got one eye on fashion, but another on bargains. This year the bowling bag replaced the Fendi baguette as the handbag of the season: but my version is from M&S, and cost just £3 in a sale.

Research by women's website Handbag.com to tie in with the launch of its celebrity handbag auction next week reveals what famous women's bags say about them.

Fifteen bags in all will go under the hammer from Monday in aid of the charity Breast Cancer Care. Up for grabs will be bags from Baroness Thatcher, Mo Mowlam and Cherie Blair as well as Jerry Hall, Emma Forbes and Lorraine Kelly.

Texan model Jerry Hall, who will be stripping off on the London stage for the role of Mrs Robinson in the Graduate, admits she has a weak spot for handbags, owning 30. "My favourite is a 1950s Cartier alligator with a real gold handle," she reveals, adding that she likes her handbags to be glamorous, reflecting her personality.

At the other end of the spectrum, down-to-earth TV presenter Lorraine Kelly favours a huge bag she bought in New York for $10 which has a pouch for her mobile phone. "My handbag reflects the fact I work - phone, notebook, diary, etc. And that I'm a mum - tissues, crayons, paper and so on."

As for Baroness Thatcher, during her reign as Prime Minister, her handbags wrought as much fear among cabinet colleagues as the steely single-mindedness of the Iron Lady herself.

It was not unknown for her to signal her disapproval by batting her handbag around at the slightest sign of dissent, leading the Oxford English Dictionary to feature the word as a verb: to handbag, "(of a woman politician) to treat (a person, idea etc) ruthlessly or insensitively".

York image consultant Sally Hanley has an interesting take on what handbags say about women.

"Royalty always carry very little, so you could say that if you carry loads in your handbag, maybe you are not as important as you think you are. It's like your desk at work. The clearer it is, the more important you are.

"Disorganised people put everything in their bags just in case they are going to need it. They want to be prepared for every eventuality, but what happens is their handbags just get increasingly large. Remember that a £50 note and a lipstick takes up very little room."

Sally says that most women could do with some helpful advice on handbags, as it is easy to create the wrong impression by carrying the wrong bag.

"Handbags are proving to be essential accessories rather than optional ones, but people have to be careful about the choice they make and what they wear it with," she says.

The must-have look this summer is the pretty, colourful, beaded bag - which is great for nights out or holidays but a no no for work, warns Sally.

Other top tips are:

u Don't wear a leather bag with summer clothes: if the outfit is delicate, the bag must be too.

u Make sure the colour of the bag co-ordinates with shoes and is preferably a lighter shade.

u Get the scale right: taller or larger-sized women should avoid dinky bags which will make them look bigger. Equally, women with wide hips should avoid a bag which rests there as it draws attention to that area.

u If a briefcase is needed for work, buy one which also has a compartment for personal possessions. This way women do not need to carry a handbag as well.

u Keep a container at home and empty handbag contents into it, picking out only the essential items each day as required. This should also cut down on time wasted looking for 'lost' items.

Sally admits it sounds like a bit of a minefield and offers this best advice: "Just remember that something for business needs to be plain and functional and something for weekend or holidays can be fun and a bit more frivolous."

And don't forget the golden rule: "Only take out with you the things you need."

Sally Hanley, image consultant, can be reached on 01904 702734

For more details about the celebrity charity auction, log on to www.handbag.com

Top five handbag facts

The earliest known handbags were carried by men. They were small 'sacks' containing pomanders, flint and money and were known as 'pockets'.

It wasn't until the 1920s that the handbag became indispensable for women, both as a functional and fashionable item.

Thousands of handbags are left on trains each year, top of the list is Chiltern Trains with 780 bags handed into lost property last year.

The most expensive handbag on sale in London just now is a Hermes black crocodile skin bag, price tag: £12,000.

Last year, a 1950s Hermes crocodile Kelly bag fetched £6,000 at Sotheby's charity auction, Passion for Fashion.