The secret to perfect cuppa? Milk in first

However in a blow for the purists, and following extensive scientific study, it now appears that those who prefer to pour milk in first may have had it right all along.

A new guide to making the perfect cup of tea may finally settle the question in a breakthrough that will be a blow to many purists. The British Standards Institution (BSI) has released a guide called Preparation Of A Liquor Of Tea For Use In Sensory Tests that sets out what it deems to be the essentials for a perfect brew.

According to the BSI, the milk must be poured into the cup before the tea, which should be brewed for six minutes.

The standard could finally end the debate around whether milk should be added to the cup before or after the tea.

But the BSI has gone further still, determining that a pot made of porcelain is an essential, and there must be at least two grams of tea to every 100ml of water.

The temperature cannot go beyond 85C (185F) when served but should be above 60C (140F) for “optimum flavour and sensation”.

The perfect pot size is apparently between 74mm and 78mm wide, and 83mm and 87mm tall. And as the average tea bag contains 1.5g of tea leaves, at least two tea bags should be used for a small pot, and four for a large one.

The BSI said the perfect brewing time was six minutes to extract the flavours from the tea leaves. The BSI is the business standards company best known for its Kitemark, recognised as a mark of excellence that is seen on everything from manholes to aircraft.