Valentine Low tries a cup of Golden Tips, which is served by a sommelier with gold tweezers to weigh out exactly 3g of tea

There are strict rules for making a cup of tea. Rule 1: leave the bag in for long enough to get a decent colour. Rule 2: put the milk in afterwards.

Today, however, there are scales, gold tweezers and a timer to make sure it brews for exactly the right length of time. There is also a lovely silver teapot, which is an altogether classier affair than the stained mug that normally does the job at home.

For I am sitting in a hotel in London, about to enjoy the most expensive cup of tea in Britain. It is called Golden Tips, it comes from Sri Lanka, and it costs £500 a pot.

This week it has gone on the menu for afternoon tea at