The screaming and yelping was explosive. Through the undergrowth hurtled a four-year-old dog of uncertain pedigree, tail between her legs, with the mangiest of foxes snapping at her back. And it wasn't just any dog - it was our dog, being driven out of our garden.

As she bolted through the door, taking most of the dog flap with her, the fox turned imperiously, skipped away behind the shed and was gone.

There is no shortage of foxes in Britain's cities. The best estimates suggest that there are some 258,000 in Britain, of which 33,000 are townies. Every year an estimated 425,000 cubs are born.

That is serious overcrowding. In the wilds of Scotland a fox's territory ranges up to 40 sq km (15.4 sq miles) but in towns it can be as little as 0.2 sq km - that's about 240 square yards. Crammed in like this, is it any wonder that they seem so noisy?

The nocturnal carousing of the fox is part of city life - who hasn't been woken by their shenanigans - but you might imagine that owning a dog would deter them. Unfortunately, in our case at least, it didn't.

As our dog, Ruby - part collie, part Jack Russell - whimpered under the dining room table, wrapping herself around my legs for comfort, the reason for the recent onset of her overnight incontinence was clear. The puddles, and worse, that had begun appearing in the kitchen seemed understandable now: the poor animal was terrified.

A call to the council pest control office proved pointless. The issue of foxes in the borough was “controversial”, admitted the woman to whom we spoke, but the council had no policy on them whatsoever. She suggested a call to the Department for Environment, Food and Rural Affairs (Defra).

The man at Defra was sympathetic and recommended Natural England's website as a source of information on urban foxes and how to deal with them.

According to Natural England, a secure bin is the key to a fox-free life. If your bins are impregnable, a fox has little or no reason to spend time on your property. But the fox that was terrorising Ruby obviously hadn't visited the website. Our bins were solid and clamped shut.

The site mentions other deterrents, but many are non-starters for most city people. An electric fence? What about our dog? What about children? In any case, such fences are not cheap, and Natural England recommends that they should be at least 2m (6ft 6in) high, buried to a depth of 45cm and topped with a sheet of smooth material at least 30cm deep.

It makes sense to ensure that there are no obvious holes in your existing garden fence, or gaps at the foot of it. But foxes are experts at breaking and entering, as well as being good jumpers.

Chemical repellents are likewise unreliable, in the absence of any conclusive proof that spreading essence of lion dung on your garden will persuade them that a pride of big cats is dozing silently in the shrubbery.

Renardine, a bone-oil solution used to deter foxes for many years, is no longer approved of (and in any case smells foul), though there are some alternative non-toxic sprays and granules for sale.

If those fail to work, though, what can you do? Rodney Calvert, a wildlife management adviser with Natural England, reveals that foxes are not a protected species, although their welfare is covered by the Wild Mammals (Protection) Act of 2006. This rules that although you can kill a fox, you cannot be cruel to it. You can trap it, provided that you don't use a leg-hold trap; and you can shoot it, but you cannot poison or gas it. Nor, since the Hunting Act of 2004, can you call in a friend's pair of lurchers to chase it away.

Calvert's advice is simply to make your fox's life as uncomfortable as possible and hope that it goes away (tricky if the den is in someone else's garden).

If you discover a den on your property - it will usually be underneath an old shed - you cannot simply pour in wet cement (too cruel). You can lightly fill the entrance with earth - so-called soft blocking - through which foxes can dig their way out, and repeat this manoeuvre several times in the hope that eventually it proves enough of an irritant to persuade the foxes to move. If the earth at the den entrance is undisturbed for a fortnight, you can assume that it is empty and fill it with concrete as a more permanent deterrent.

Such solutions are slow, though, and far from guaranteed to succeed. It is of little comfort to Ruby that the average urban fox lives not much longer than 18 months - according to Natural England, even if you call in the pest controllers, evicting one family of foxes from your garden can simply create space for another family to move in.

With limited options, I will be out patrolling our turf with a cricket bat last thing at night, in hope of catching the fox that terrifies Ruby unawares.

Alternatively, putting my faith in the old wives' tale that foxes are repelled by anything that smells strongly of testosterone and meat, I could always follow Calvert's jocular suggestion and spend an evening drinking, follow it with a curry, then relieve myself over the fox's point of entry to our garden. Although what the neighbours would make of a hung-over, middle-aged man cursing and urinating against his fence at dawn is anybody's guess.

Into the trap: if all else fails

Although some pest control agents will deal with foxes, most stick to cockroaches and rats. One who is not afraid to admit disposing of them permanently is Mike Batt, from Guildford in Surrey, who has been tackling urban foxes for eight years. Last spring and summer his stock of 16 traps was in constant use. He hires out two traps at a time, at a cost of £80, baits them with cat food, then waits. When a fox is caught, a bullet in its brain costs the customer a further £60.

Times recommends

• Live chat: Thrifty ways to update your winter wardrobe
• Is anybody out there really listening?
• Nutrition Q&A: Will eating late make me fat?