THERE’S a chemistry to the perfect afternoon tea: just as there is to the perfect romance. The neatly trimmed triangular sandwiches, the scones and cream, even the tea you drink - they’re all made up of molecules. And it is the way those molecules combine and interact that determines how your tea tastes.

All will be revealed at Betty’s Café and Tearooms in St Helen’s Square on June 17, at a unique Festival of Ideas event where University of York chemistry professor David Smith will talk about the ‘science of the scone’.

The talk will explore what makes afternoon tea such an addictive and guilty pleasure, considering the bits of chemistry which make a luxury afternoon tea special.

He’s promising a couple of surprises along the way. “I want to reveal the chemistry going on in a context where we tend not to think of it,” he says. “You imagine that afternoon tea at Betty’s is a perfectly ordered ritual – the perfect sandwich, cake, cup of tea – but it’s much more chaotic beneath the surface, once you get down to the molecules and the chemistry.”

There will be practical demonstrations too. “And we’ll go beyond just the scone,” Prof Smith promises.

lThe Science of the Scone, Betty’s Cafe and Tearooms, St Helen’s Square,12:30 on Tuesday 17th June. Visit yorkfestivalofideas.com for more details