Guinness drinkers have been issued with wartime-style ration cards to help combat a national shortage of the famous black stuff.

Makers of the iconic Irish stout, Diageo, have said "exceptional consumer demand" in the UK is forcing them to restrict supply at one of the most party-packed times of year.

One original-thinking boozer has come up with a plan to help punters still enjoy the black and white beverage by issuing "ration cards" requiring customers to purchase two different drinks before they can sup on a Guinness.

Posting on their Instagram page on December 12, the Old Ivy House, in Clerkenwell, London, wrote: "In these difficult times… Ladies and gentlemen we are being rationed.

"The #blackgold is in short supply countrywide. It’s true. We are down to 3 barrels with our next delivery not due until next Wednesday, at the busiest time of the year.

"Ask at the bar for your ration card. We’ll get through this together."

Co-owner Del Currie told the Morning Advertiser: "Our pub is all about making lemonade out of lemons. Instead of freaking out and saying, 'There's going to be no Guinness for Christmas', we thought we'd have a bit of fun with it.

"We started doing it last night and it ended up being quite fun - people really enjoyed it."

According to the Sun, data from the food and drinks industry research firm CGA revealed volumes of Guinness sold from kegs were up more than 20% between July and October.

Diageo said: "We have maximised supply and we are working proactively with our customers to manage the distribution to trade as efficiently as possible."

Landlords have been reported to be "panic buying" Guinness with one owner saying a shortage will “cripple him”.

The landlord of an Irish pub in Liverpool, Steven Crosbie, says that Guinness is his top-selling beverage. He told the BBC: "If I can't get it in it will probably cripple me."

Steven typically gets 12 50-litre barrels per week delivered from his distributor, yet last week he said that he could only get one. This sentiment has been echoed throughout the industry as owners are struggling to keep up with the demand.