So sharp you won't cut yourself

Yes, I confess, this is a staged photograph. Our kitchen doesn't look like this though, if it were big enough and one of the corners could be veiled off, this is what you might see behind the curtain. It's all to do with that urban (domestic?) myth that you're more likely to injure yourself with a blunt knife than a sharp one. A dull knife means you need to exert more pressure and that pressure may get misdirected.

Our arsenal of sharpeners starts with the steel in the foreground. It was quite expensive and the blade is embedded with diamond dust. It's OK for toning up a knife that has merely lost its edge but it's not the device you'd use if, for urgent reasons, you needed to convert a butter knife into a carver.

To the right is a Carborundum stone held in a wooden frame. This is slowish but eminently controllable and I would use it to transform a really blunt knife if it were also necessary to maintain the appearance of the blade.

Finally the double grinding wheel with the non-optional safety glasses. Brush one side of the knife blade against the wheel for five seconds, then the other side. The device is ugly, surprisingly cheap, belongs in a workshop and is frighteningly efficient.

TECHNO-ART "Rififi" is a French burglary caper film that predates the word caper. Famous for the 15-minute passage without dialogue. It's particularly good on the technology of burglary. Entrance to the target room is made down through the ceiling and the thieves need a method of preventing debris from dropping on to the floor below and starting the burglar alarm. Simple - insert a folded umbrella through an initial small hole then open it up. Immobilise the burglar alarm? Squirt the contents of a fire extinguisher into it.

Don't need it, never have punctures

Can you say - hand on heart - what the pressure is in your car's spare tyre? I can't but then I don't have to. Over a decade ago I was given an electric pump that plugs into the car's cigarette lighter socket. It seemed like a utilitarian gift at the time but down the years I've used it a couple of dozen times.

Because otherwise a spare tyre can be a delusional form of re-assurance. Puncture in the middle of the Massif Central and a half-deflated replacement is only slightly more valuable than no tyre at all. Worse if you're tempted to use it in that state.

The pump has a further benefit. It's easier to bring tyres up to the correct pressure in your own driveway than on a harassed garage forecourt (where you may also have to pay for the privilege). It's not all gravy, however. The pump is noisy, in my case the car engine must be running and it seems to take an inordinate length of time to add 2 - 3 psi. Also, the gauge on the pump is not accurate enough and you need a separate traditional gauge. But it beats thumbing a lift.