After conducting extensive research among its members, The Royal Society of Chemistry has concluded that anything under the prescribed height cannot be said to have successfully risen.

And cooks wanting to rustle one up need to arm themselves with carbohydrate + H2O + protein + NaCl + lipids (flour, water, egg, milk and fat), said the scientists.

Chemist and Yorkshireman Dr John Emsley was tasked with drawing up the definitive recipe and dimensions after the society was contacted by a bewildered cook whose pudding refused to rise.

Englishman Ian Lyness, living in The Rockies, was looking for a scientific explanation for the fact that his Yorkshires came out flat when he cooked them in Colorado even though they rose when he made them in other parts of America.

The RSC is now investigating whether the mountain air is causing the dish to flop.

In the meantime Dr Emsley has spoken to a series of chemists working in the food industry about the perfect, chemically balanced recipe.
He warns darkly about the dangers of putting the prepared batter in the fridge and stresses the importance of getting the fat really hot.

Dr Emsley also claims that cooks born outside of Yorkshire have a natural disadvantage and will never manage to create a truly perfect pudding. But the Society admits there is little scientific evidence to back up this particular conclusion.

"It's in the blood and instinct of people born and raised there. You can always tell from the look and taste if the cook has the right touch and it is almost pitiful to observe the stuff that comes from some southern ovens - flat, pale and soggy much of the time."

He added: "I have seen many grim results from people who have tried to get their Yorkshires to rise. They frequently made gross errors. After all, cooking is chemistry in the kitchen and one has to have the correct formula, equipment and procedures.

"Some amateurs even place the batter in the fridge first. What kind of foolish act is that?".

Once the perfect pudding has been achieved then cooks who really want to follow tradition should remember that in Yorkshire the dish was only ever served as a starter with gravy.

Thrifty housewives used it as a ploy to ensure that diners did not need to eat as much of the expensive meat course.

And there is no need to save the recipe just for savoury meals - Yorkshires were often eaten as a filling dessert.

The Society is publishing its advice on how to make the perfect 4in pudding as part of its forthcoming focus on food

The Royal Society of Chemistry Yorkshire Pudding

Ingredients:
Tablespoon and a half of plain flour
1 egg
Half milk, half water to make a thin batter
Half a teaspoon of salt.

Method:
Put flour in a bowl, make a well in the middle, add the egg, stir until the two are combined then start gradually adding the milk and water combining as you go.
Add the liquid until the batter is a smooth and thin consistency.
Stir in half teaspoon of salt and leave to stand for 10 minutes.
Put beef dripping into Yorkshire pudding tins or into one large tin but don't use too much fat.
Put into hot oven until the fat starts to smoke.
Give the batter a final stir and pour into the tin or tins.
Place in hot oven until well risen - should take 10 to 15 minutes.