"It was a thrill to have the show back and it looked more stunning than ever," wrote The Independent's reviewer.

"By the end of the episode it is clear that the stage is now set for a war of truly epic proportions," wrote Jess Kelham-Hohler of the Evening Standard.

Yet Digital Spy's Alex Mullane did feel the episode - entitled Dragonstone - was "a little underwhelming in places".

The first episode of the show's seventh series was broadcast in the US on Sunday evening and in the early hours of Monday morning in the UK.

Only one more season of the epic fantasy saga, inspired by the works of author George RR Martin, is planned after this one.

Dragonstone opened in typically gory fashion with members of the late Walder Frey's house dying in numbers after imbibing poisoned wine.

It also featured the introduction of a new character, played by the Oscar-winning Jim Broadbent, as well as a cameo from pop star Ed Sheeran.

Reviews of the episode welcomed Broadbent's performance as Archmaester Marwyn, with the Hollywood Reporter saying he "fits into this ensemble flawlessly".

Yet critics were far less complimentary about Sheeran, whose appearance as a soldier was dubbed "jarring" and "unsubtle" by The Independent's Christopher Hooton.

In his role as an unnamed singing soldier, the chart-topping performer is seen telling Maisie Williams' Arya Stark that the song he is singing is "a new one".

According to the Daily Mirror, the exchange "could only have been more awkward if he'd winked at the camera after and said 'Available at all good record stores'."

Many reviewers felt the episode's main function was to set the scene for the rest of the season, with Empire's James White calling it "a fairly standard kick-off".

Yet this did not stop Forbes' Erik Kain proclaiming it to be "one of the best, most engaging season openers... filled with brilliant scene after brilliant scene."

Fans too have been in raptures, with Chris Gutierrez claiming the episode showed Game of Thrones to be "quite possibly the best show ever made".

"Arya madness. Ed Sheeran cameo. Sansa looking phenomenal. Dany finally touching Westeros. Dragons. Game of Thrones well & truly back," raved fellow Twitter user Luna.