She's only been in the house 10 seconds, and already Lorraine Wilson has spotted a security flaw.
"This front door doesn't shut properly", she announces, giving it a couple of firm shoves.
"Ah, yes, well, there's a bit of an art to it," I explain. "When you close it, you have to lean against it with your shoulder, then give it a bash with your knee, otherwise it comes open again."
She nods, and makes a note in her exercise book. It's her job to get the residents of south-west London thinking in a more intruder-unfriendly way, and having a front door that flaps back and forth in the breeze is hardly the best way of deterring burglars.
Mind you, she can't fault the door's thickness; Metropolitan Police guidelines recommend a minimum depth of 44mm, and ours is a generous 45mm. That's our first line of defence, too; we've got an inner door that measures 46mm.
"Not bad," nods Lorraine, with mild approval. "Could do with three locks instead of two, and the mortice should be in the middle rather than at the bottom. But at least it's a pretty sturdy construction."
So it's seven out of 10-ish for the frontal access area, but then the side alleyway lets us down.
"Oh dear," sighs Lorraine, shaking her head and surveying what I had assumed to be our unassailable, seven-foot-high side gate. "What you've got is a very convenient climbing frame."
And she demonstrates how a burglar could grab hold of the drainpipe in one hand, our neighbour's fence with the other and, using the gate handle as a stepping stone, be up and over the top of the gate in a jiffy.
Maybe so, I reply, but he wouldn't be banking on those nasty hidden nails at the top of the gate frame; the ones that used to hold the trellis in place.
"Yes," says Lorraine. "Well, those nails are illegal, and if someone were to hurt themselves climbing over your gate, they could possibly sue you for negligence."
What? Even if they were fiendish intruders intent on ransacking our home? Apparently so. Of course, I could deter them by coating the gate and drainpipe in slippery, anti-climb paint - but according to Lorraine, I'd still have to put up a notice warning them! Talk about odds being stacked in favour of the criminal. It's enough to turn Frank "Ooh Betty" Spencer into a raving Charles Bronson.
Fortunately Lorraine has a third way to suggest, which lies somewhere between installing machine-gun nests on the roof and hanging "Please Burgle Me" signs on the front door.
"These are quite effective," she says, showing me a picture of some rubber spikes. "You fit them to the top of a gate or fence, and they're hard enough to deter a burglar, but not sharp enough to wound."
Just the job. That's the best thing about a visit from Lorraine; she doesn't terrify you and go away, but steers you towards the sort of security measures that suit your particular home. She has an encyclopaedic knowledge of local stockists and locksmiths.
A former paralegal adviser, she works for Wandsworth Council as part of its Wandsafe community support team and works closely with local police.
"Most of the time, I'm visiting people who've just been the victims of a burglary," she says. "They're my priority, but, given a few days' notice, I'm always happy to come round and advise people on how to avoid a burglary."
Which means the next step is our garden shed.
"See this spade, these garden forks?" she says. "Any one of these could be used by a burglar to force open a window or door. Clearly, you want to keep your shed well locked up, but if you can't make it 100 per cent secure, at least chain these tools together with a bicycle padlock - preferably one that's combination-operated so you don't have to keep fetching the key. It's much harder for an intruder to use these tools effectively if they're all joined together."
Good idea. As is her suggestion about where - and where not - to store valuables inside the house.
"If you've got jewellery or other things that are worth a lot but which you don't often use, the worst thing is to leave them in a little dish, or put them in a top drawer. That's the first place a burglar looks. The simplest solution is to put them in a safe; it doesn't have to be big, it doesn't have to be expensive; the cheapest is around £15
"It doesn't even have to be ugly, either. A friend painted sunflowers all over hers, fixed it underneath a transparent table top, and uses it as a coffee table. Apart from anything else, it's the perfect camouflage."
Amid all her tips and booklets on British Standard locks, Lorraine insists the most effective burglar deterrent is attitude.
"Don't leave your doors and windows open, don't let strangers or bogus callers into your house, don't think it'll never happen to you. It can," she says.
"Most burglars are opportunists. The best thing you can do is deny them that opportunity."
Ways to beat the burglars
Rubber spikes: effective but not illegal (unlike razor wire). Put them on top of walls and fences. Made by the London and Lancashire Rubber Company (01992 625625)
Full metal box: store your most valuable valuables in a mini-safe.
Cunningly concealed keys: Keep keys well out of reach of your letterbox (thieves reach in with canes and fishing rods). Find hiding places to hang them, such as under kitchen unit overhangs.
Passive infrared lighting switch: turns lights on automatically when it gets dark; better than a clock-timer because it comes on at variable times.
Advice: not every council has a free security adviser such as Lorraine Wilson. Try the crime prevention officer at your local police station, or the police architectural liaison officer, who advises on crime-free design at home and at work. Failing that, call in for the booklet "How Secure Is Your Home?", text of which is available on the website www.met.police.uk/crimepreventionReuse content