A proper Yorkshire pudding must be 4 inches tall. It's official. The Royal Society of Chemists says so. The second key qualification is the cook must have Yorkshire blood. "It's the instinct of people born and raised in Yorkshire. You can tell if the cook has the right touch," scientist John Emsley told the BBC. Perhaps that's why my Yorkshire mother makes puddings like shoe leather - she was born in Kuala Lumpur.

The impetus behind approaching a Yorkshire pudding with a tape measure was an inquiry to the BBC from Ian Lyness, living in the US, as to why his puddings cooked in Colorado were always flat while in other parts of the country his puddings soared like larks.

The RSC, which I hope is not taxpayer funded, is now working on whether the Colorado mountain air is making Lyness's puddings sink. "One has to have the correct formula, equipment and procedures," explained Mr Emsley, himself a Yorkshireman. "To translate the ingredients into chemical terms, these are carbohydrate + H20 + protein + NaCl + lipids."

I'm not sure I could produce anything from that recipe. Here's a better one for a single pudding:

1 1/2 tablespoons plain flour dumped into a bowl. Make a well and add one egg. Stir until combined, then gradually add a mixture of half milk, half water until the flour/egg combination is smooth and the consistency of single cream. Add 1/2 teaspoon of salt and stand at room temperature for 10 minutes. Then pour beef dripping (fat) from around the roasting meat into a hot tin. Put it into the oven until it smokes, remove, pour in the batter, return to the oven and bake 10-15 minutes until 4 inches high.

Remember: Yorkshire pudding was originally poverty food. It was always served as the first course, alone with gravy and the Yorkshire-accented incantation, "Them as eats most pudding gets most meat". The idea was you'd be so full of pudding you'd not want much of the very expensive, and consequently small, roast.