Scientists say the perfect Yorkshire pudding should be 4 in tall.
Scientists say that the recipe for the perfect Yorkshire pudding lies in its size.
After much research The Royal Society of Chemists (RSC) has published guidelines saying a pudding has to be more than 4in (10cm) tall.
According to scientist John Emsley, another ingredient for success is native Yorkshire blood.
He said: "It's the instinct of people born and raised in Yorkshire. You can tell if the cook has the right touch."
The judgement followed an inquiry from an Englishman living in the USA who e-mailed the society seeking scientific advice on the chemistry of the dish following a string of kitchen flops.
Ian Lyness had contacted the RSC to get an explanation for why his attempts at cooking traditional Yorkshire puddings in Colorado had gone flat.
In other parts of the USA Mr Lyness had successfully produced puffy, towering puddings.
The RSC is working on whether the Colorado mountain air is causing the pudding to flop.
The inquiry prompted Mr Emsley to look into what makes a perfect pudding.
Mr Emsley, who comes from Yorkshire, said: "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.
"To translate the ingredients into chemical terms, these are carbohydrate + H2O + protein + NaCl + lipids.
"Some amateurs even place the batter in the fridge first. What kind of foolish act is that?"
According to the RSC the pudding should always be served as a separate course before the main meal, and the best gravy made from the juices of a roast joint should be used.
Yorkshire housewives served Yorkshire pudding before the meal so that they would eat less of the more expensive main course.