Greene King is to bring its rarely seen 5X beer to next week’s Great British Beer Festival, at Olympia in London.

The two-year-old oak-aged beer is never usually sold, instead forming the basis of two of Greene King’s well-known brands — Old Crafty Hen and Strong Suffolk.

The 12.5% ABV beer uses a secret recipe and is then aged in giant oak vats at Greene King’s Westgate Brewery in Bury St Edmunds. One of just a handful of brewers who still use the oak-aged method, Greene King’s 5X beer is often described as the finest brandy of the brewing world.

Greene King master brewer, Craig Bennett, said: “We have limited stock of 5X as it takes a minimum of two years to age, so it’s a pretty precious commodity. Most people at the brewery never get the chance to try 5X in its pure form, so it’s a bit of a treat to bring it along for the Great British Beer Festival for festival-goers to experience it.”

Greene King will be serving 5X in taster glasses and thirds and will have a limited supply, so when it’s gone it’s gone!

Festival organiser, Catherine Tonry, said: “We are delighted to welcome Greene King back to the festival as our headline sponsors this year. The Great British Beer Festival provides a unique opportunity to try rare, one of a kind and exclusive festival brews, as highlighted by the iconic 5X brew.

“As the only place for the public to try this beer, I can imagine there will be quite a queue from the Greene King stand next week!”