Tim McKenna, whose grandfather emigrated from Co Monaghan to England in 1946, recently shared a photograph on Twitter of the rare half-pint bottle of Guinness.

"Talk about best before dates!" McKenna tweeted with a picture of the rare find on Monday, April 17.

"Found a half-pint bottle of Guinness with a cork top in my mum's cupboard.

"Fifty years old?"

Talk about best before dates! Found a half-pint bottle of Guinness with a cork top in my mum's cupboard. Fifty years old? pic.twitter.com/qCFPDu5BE7

— Tim Cycles The Coast (@TimMcKenna01) April 17, 2023

He later said that he believes his grandfather brought the bottle back from a trip to Ireland in the 1960s but was unable to say why it had remained unopened. 

"Just don't know why my grandad brought it back from Ireland but didn't drink it!" McKenna said, responding to a Twitter user who inquired about the bottle. 

The rare artifact is in a good condition considering its age and still boasts its original Guinness label. 

Although McKenna was unable to give an exact date for the bottle, it dates back to 1969 at the very earliest. 

To the dismay of many Irish bartenders, Guinness introduced standardized metal caps to replace corked bottles, arguing that corks were unhygienic. The introduction of metal caps also allowed Guinness to have greater control over the quality of the product. 

A number of Guinness drinkers reacted angrily to the change, with several people telling RTÉ that they would not drink Guinness unless it was corked. 

"I wouldn’t go into a public house unless there was a cork bottle in it," one Drogheda local told RTÉ in 1969. 

"I’d sooner have a cork bottle any time...because it tastes better, tastes smoother," said another.