It's been quite a long time since they've shared a scene together on screen, but Jason Momoa and Emilia Clarke clearly struck up a strong friendship on 'Game of Thrones'.

The American actor, who played Khal Drogo in the series, has regularly posted pictures of the pair over the years whenever they bump into each other. The latest saw him surprised by his former screen missus at his 40th birthday bash.

The Guinness-loving 'Aquaman' star was thrown a surprise party by friends at the 5-star Rosewood Hotel in London, even though his birthday isn't until tomorrow - and it even featured a custom Guinness tap that featured his face on the head.

His former co-star posted a picture of the pair to Instagram, with a second picture of her in an oversized bathtub. Her caption read: "With you I feel 2 feet small.  X 2  @prideofgypsies HAPPY FREAKING BIRTHDAY BABY! An oversized bath tub of happiness for another year of you. #moonofmylifemysunandstars  #finallyabathbigenoughtobathadragonin  #thenbrokecosispentallmymoneyonbubblebath"

See how the surprise panned out below: