King Charles poured the "perfect" pint as he celebrated the opening of the new Guinness brewery in London yesterday morning. Enthusiastically going behind the bar to learn how to pour a pint of the world-famous Irish dry stout, the King quickly mastered the art of pouring a pint of Guinness into one of its trademark glasses featuring the harp logo.

The audience applauded as the King poured an "absolutely perfect" pint of stout, having been told to hold the glass at a 45 degree angle while pouring, filling it to three-quarters full and letting it settle before topping it up just above the rim. Charles brushed off the congratulations and simply said: "If you say so!"

Leo Ravina, 23, had the honour of talking the King through the process and remarked the King's pour was "absolutely gorgeous" and said "you've done this before I see". As he took a sip of the pint, the King ended up wearing a white moustache as the creamy white froth left an imprint on his upper lip.

During the King's visit, he met graduates of an award-winning hospitality course and was shown how to "print" a Christmassy image of holly on the head of a pint. As the King used a machine to mark the top of his pint, he said the result was "amazing. Just fantastic. The trouble is it doesn't look real!" He couldn't believe it was all done through a phone.

The inks used to create the images are made from barley, or carrot and beetroot. After the print was made on top of the pint, the King said: "So you want me to ruin that now do you?" Having tried the drink for himself, he says "it is great stuff" and asked the barman if he ever gets Guinness stuck in his beard.

Led by the Master Brewer, Hollie Stephenson, the King toured the microbrewery and met the team who create special Guinness brews, which are unique to the £73m Covent Garden site.

He was shown the Guinness range, including limited-edition seasonal brews. The King particularly enjoyed the Apricot beer and said the ginger, cinnamon and nutmeg combination in the Winter Warmer was a "very good combination".

The King enjoyed his pint in the 232 Bar - named after the precise temperature that gives Guinness its signature roast - where he met graduates of Diageo's Learning for Life and The King's Foundation ‘Introduction to Hospitality' course.

Diageo's programme, led by chairman Sir John Manzoni, offers free hospitality training for those looking to build a career in the industry. The new brewery has been named its UK southern hub. The King went on a brief walkabout to greet members of the public braving the rain, before walking the short distance to Old Brewer's Yard, to join in on Christmas celebrations with local community groups and businesses who have close ties to the Brewery.

Here, the King was met with an array of Guinness containing treats, where he remarked that the large Guinness Cake was "seriously dangerous". He heard Christmas carols sung by The Covent Garden Chorus, who he asked, with jest, if they were a part of the "Royal Opera House Choir".

The Open Gate grand opening finished with the King unveiling a plaque in the courtyard to mark the official opening of the Brewery, which also includes a visitor experience, restaurants, shops and events space. The London site is the fourth Guinness Open Gate Brewery site globally. The original Guinness Storehouse, at St James' Gate in Dublin, celebrated its 25th anniversary this year and has welcomed more than 25 million visitors since opening.

Today's engagement marks the first public engagement the monarch has undertaken since his cancer message on Friday. The King told the nation that from the New Year his treatment would be reduced.