Going on and on and on constantly may be a good idea. Particularly for the Sunday lunch

I DON’T have an Aga; never really wanted one – although I’ve always loved them when I’ve found them in other people’s houses on a cold winter’s day. But even if I decided to get one, I’d have to knock the house down, crane in the oven and rebuild a redesigned house. We’ve a lovely kitchen but it’s not the right shape for an Aga, getting oil or liquid petroleum gas to it would be a struggle (we live off the natural gas network) and I don’t fancy feeding it coal.

But people who have them swear by them; not least because they say that the food that emerges from the Aga’s ovens is better than that from the ovens of the rest of us mere mortals. How can that be? After all, once the stew’s in a pot or the roast’s in its tin, surely an oven’s an oven?

Well actually, no. It turns out you really do get what you pay for. And maybe these Aga advocates have something.

It’s worth looking at the standards to which ovens have to be built. Nowadays they all have to comply with, and display, efficiency ratings. Simply put, that’s how much energy they use and such information helps us choose how much we wish to contribute or otherwise to global warming. Of course, there’ll be safety standards including shatter-proof glass doors, double electrical insulation and so on.

Then there’s how clever the thermostat is. That’s the little robot every electric or gas oven has to control the temperature. Now, you may think that’s not that important. After all, once you know that turning the knob to a particular position gives a rightish sort of temperature, surely that’s enough. But actually, the thermostat in most ovens is a fairly crude bit of kit. When the temperature gets a bit too hot, it turns the gas down or electricity off. And when it cools down somewhat, it turns it back up or on again. So really your oven goes up and down in temperature and the standards that the manufacturers have to comply with only say that that temperature has to be within so many degrees of what it’s set at. Typically most electric ovens go up and down by up to 10 degrees either side of the set temperature. And that means that if you think you’ve set your oven to 180°C, it could actually be oscillating between 170°C and 190°C. That’s 20 degrees of difference.

Meat doesn’t actually like having some heat applied, then being allowed to cool, then having heat applied again and so on until it’s ready, but that’s what’s happening in most ovens. It tends to turn out better if the temperature’s kept nice and constant. The meat’s usually more tender and there’s less shrinkage and, therefore, waste. It’s why we spent £7,000 on an oven for the restaurant and £13,000 on each oven for our banqueting suites at Shotton Hall and Seaham Town Hall. We wanted the best ovens you could buy and one of their qualities had to be the ability to maintain a really constant temperature. Surprisingly, most ovens can’t do that; even most common commercial catering ones. But it means we can cook things extremely accurately, particularly at low temperatures enabling us to cook the tastier cuts of meat, long and slow, overnight.

Agas, particularly because of their considerable bulk, tend to hold their ovens at constant temperatures and this explains why their proponents reckon they’re brilliant cooks. And it’s why, if you’re not buying an Aga, and can afford it, it’s worth buying a really good normal oven and checking how clever its thermostat is.

And if you really wanted to impress, you could ask the salesperson about the thermostat’s hysteresis (which is actually how closely it controls the oven). But beware: he may misunderstand or, worse, take offence. So be prepared.