And the secret to her longevity and energy may lie in a bedtime tradition which the monarch religiously follows. According to her cousin, Margaret Rhodes, Elizabeth II always drinks one glass of champagne each night before bed. While there is no word on what brand she drinks, it’s almost certainly one of the eight, including Bollinger, Krug, Lanson, and Pol Roger, that have been granted royal warrants.

A brand can apply for such a status after being served in the royal household for at least five years.

These include, but are not limited to, Agnostura bitters, Bacardi-Martini and Johnnie Walker Scotch.

The British monarch is known to enjoy a tipple or two during the day and by all accounts is partial to gin and Dubonnet.

Infused with citrus and herbal notes, the gin costs £40 for a 70cl bottle and is 42 per cent ABV.

The royal gin was quickly snapped up by fans and sold out within eight hours.

A spokesperson for the Royal Collection Trust said it was “delighted with the response” to the gin and that more orders had been placed with the supplier.