Is he a Hugh or a Hewitt?

We ladies are given plenty of tips on how to improve our lives - get a flat stomach, chip away at that glass ceiling, give birth without going up a size - but it's clear that what we should really be focusing on is the quality of our ex portfolio.

Just days into the new year and already we've been reminded of the importance of picking boyfriends wisely. On the one hand, we've had those heart-warming shots of Hugh Grant pushing Damian's pram around St Moritz, and generally being an ideal ex (attractive, attentive, loyal, discreet).

On the other, we've endured that slimebag James Hewitt, touting his bag of Diana's love letters around Britain and now the States, and generally being an ex from hell (oily, attention seeking, disloyal).

Finding that one special person is all very well, but more important is to find a man who, despite having known you carnally, read your diary and received your embarrassing love notes remains honourable. What you don't need is a human time bomb.

So how can you tell if you have a potential Hugh or a Hewitt? There are a few key identifying factors even in the earliest stages of a relationship.

Firstly, does he have a life? We now know that Diana was hardly sparing with her affections, but the reason her lovers are not all queuing up to spill the beans on CNN is that they are surgeons and art dealers, not jobless, friendless and desperate for a leg-up.

Then there's the matter of parity of status. Hugh and Liz are in the same league; had he been a lowly runner she'd met on the set of a movie, the temptation to kiss and tell might have proved irresistible (see Hewitt). As it is, he has too much to lose to tell his story.

So, test two is, do you have enough friends and ambitions in common to make it worth staying in each other's good books?

If he shows signs of resenting your lifestyle or is jealous of your career then he is a prime Hewitt candidate. The Hewitts of this world have nothing to lose. And, more than anything, a Hugh will never want to lose your friendship.

Hugh and Liz were friends before they dated, became business partners, shared a home and weathered the storms of success and scandal side by side.

They go too far back to betray each other. Hewitt and Diana were never friends. He was, so she mistakenly thought, her knight in khaki, her soldier hero. Their relationship was all flirting at polo and illicit trysts. They never shared a bathroom or a gas bill.

Test three: be sure that you have a relationship built on mutual respect, not just great sex. It will make it much harder for him to share your personal foibles with the lads after it's all gone wrong.

Last, but not least, ask yourself if your scores are even. A potential Hewitt can be defused and transformed into a Hugh by simply having an ace up your sleeve to match any embarrassments they might air in the future. Two dirty secrets cancel each other out.

I'm betting that Liz and Hugh have evenly matched indiscretions, which is just what the doctor ordered. Diana, unfortunately, is not here to confirm any of Hewitt's intimate shortcomings or, indeed, to blush at his revelations.