Chocolate digestive biscuits have graced our tea breaks and cuppas for 100 years - but now McVitie's have admitted we've been eating them all wrong. McVities' favoruite was launched as the 'Chocolate Homewheat Digestive' in 1925, 33 years after the plain variety whose name was inspired by the belief the recipe's baking powder would boost digestion.

But despite 80 million packs of chocolate digestives sold every year and them being named our favourite biscuit to dunk into a cup of tea, McVities have dropped a bombshell about the way we actually hold them. And amid the centennial anniversary celebrations - which saw landmarks lit with bright images of the treats - the has made us see them in a completely new light.

Anthony Coulson, general manager at the company's chocolate refinery and bakery in Stockport, Greater Manchester, said the teatime staple was meant to be eaten - chocolate side down.

Explaining how the side was designed to rest on your tongue as you ate it, Mr Coulson added: "It's the world's most incredible debate, whether you have the chocolate on the top or the chocolate on the bottom.

"One of the very first things I learned when I joined McVities was chocolate side down to eat the digestive.

"Now up until then I'd always eaten it the other way round - I still do if I'm totally honest - but you can do it exactly how you want to do it.

"It's because the tongue gets the chocolate straight away, it starts to melt, starts to get the flavour and away you go - makes sense right?"

McVities, which first began as a small shop on 's Rose Street in 1839, first developed the recipe for its digestive biscuits in 1892 - nearly a decade before the end of Queen Victoria's reign.

Its recipe is credited to an employee named Alexander Grant. The Stockport factory opened in 1917, with the chocolate digestive launched eight years later.

Lynn Loftus, who has worked at the factory for 36 years, called the biscuit "timeless", adding that she thought it would be around for many years to come.

Craig Leech, who has worked at McVitie's for 21 years, started off in the factory by putting the chocolate on top of the biscuits.

"I just come in with a positive attitude. I know the people and the products inside out," said Mr Leech, who is now a planning manager for the refinery.

Alix Knagg, who has been working there for six months, said the chocolate digestive was "still a great product 100 years on".

And although people might think of the chocolate digestive as being topped with chocolate, the company has said that as the plain biscuits pass through a "chocolate reservoir", the chocolate actually coats the underside of it.

A McVities spokesperson explained: "When we make our McVitie's chocolate biscuits - whether that be Chocolate Hobnobs, Chocolate Digestives, or Jaffa Cakes - they go through a reservoir of chocolate on the production line.

"This essentially "enrobes" the bottom in chocolate - so we can confirm that the chocolate is officially on the bottom of the biscuits."

McVities previously worked with scientist Dr Helen Pilcher to discover what the 'optimal' dunking conditions were for their most popular products.

She revealed that the average biscuit should absorb 20 per cent of its original weight in liquid for the best dunk.

When it comes to Chocolate Digestives, Dr Pilcher says the optimal dunking time is 3.6 seconds, and you'll be in the dunking 'danger zone' if you get close to 12 seconds.

She also advised dunking the chocolate biscuits in Earl Grey tea instead of an English Breakfast.

"Taken with Earl Grey tea the chocolate mixes beautifully with the bergamot, to make a liquid chocolate orange flavour."