But the post-mortem will take time, as Australia's delegation try to untangle what happened in the last hour of the competition; sources say Mauboy came in fourth place in her semi-final which makes the sharp drop to 20th place in the grand final all the more surprising.

With a show which featured vikings, jets of fire, clucking singers, vampires and the annual guest appearance by a stage invader ... say what you like about the Eurovision Song Contest but you can't say it doesn't deliver.

Australia and 25 other countries battled it out on the Eurovision grand final stage hoping to take home Europe's prized music crown in front of an audience of more than 10,000 fans who were packed into Altice Arena in Lisbon, Portugal.

But the event was barely an hour underway before proceedings were interrupted by a serial stage invader who snatched the microphone from stunned UK entrant SuRie.

The stage invader was intercepted and the microphone was returned to SuRie's hand moments later and, as she resumed her performance, cheers erupted in both the arena and the adjacent press centre.

The European Broadcasting Union, which organises the event, confirmed the stage invader was in police custody and that the UK delegation had declined an offer to repeat the performance during the live telecast.

"The EBU regrets a stage invasion took place during the UK performance at the Eurovision Song Contest in Lisbon this evening," the EBU statement said. "The person responsible is currently in police custody."

"The UK singer SuRie and her team were offered the option to sing again but decided not to because they were extremely proud of her performance and have decided that there is absolutely no reason to perform the song again."

Fairfax Media has identified the stage invader; he is an "an anti-media conspiracy theorist" who was recently involved in a similar incident at the BBC studios in Belfast and at the UK National Television Awards.

Australia's entrant Jessica Mauboy has been on the ground in Lisbon for two weeks refining her performance and has, in both the second semi-final and the grand final rehearsals and jury show, secured all three.

Mauboy has performed the song on the Eurovision stage twice in full rehearsal and eight times in competition; speaking ahead of Sunday morning's grand final the 28-year-old described it as "a magic moment".

Eurovision requires four performances for each heat, including a "jury show" which is assessed by a professional jury and the live telecast, which is voted on by the TV audience. The two scores are then integrated to find the final result.

Australia has a strong track record at Eurovision, ranking 5th, 2nd and 9th in our three past years of competition, but 2018 is an unusually strong year and there were at least a half-dozen countries expected to dominate the competition.

The final result - 20th place - will no doubt leave the Australian delegation assessing their long-term future in a competition which dramatically declared its fealty to the European continent this year.

Among the highlights of the grand final were stunning performances from Eleni Fouriera (Cyprus), featuring Spice Girls-inspired backing singers, Elina Nechayeva (Estonia) in a giant projector screen dress, and Israel's Netta, sporting crazy hair and mixing Bjork-like squeaks and clucks into her performance.

Some of the bigger set stage pieces included Denmark's Rasmussen, sporting Viking boats, beards and hoods, and Moldova's DoReDoS, who, if you weren't looking too closely, looked for a moment like a stage musical starring David Campbell and Lucy Durack.

One of the most powerful moments in the telecast was last year's winner Salvador Sobral performing Amar Pelos Dois with legendary Brazilian composer, singer and activist Caetano Veloso.

Though is officially discouraged, clusters of European countries often vote in blocs, giving each other their highest scores, such as Cyprus/Greece, Denmark/Finland/Iceland/Norway/Sweden, Estonia/Latvia/Lithuania and so on.

Though Australia, a relatively new entrant in the competition, has not fallen into a voting bloc there is a noticeable trend identifying which countries tend to score us well; they include Sweden, Denmark, Iceland, Poland and the United Kingdom.

And this year, in a shift which will have the Eurovision cognoscenti discussing the fine print for some time, there were dramatic shifts in jury and audience voting, breaking with traditional blocs and sending points all over Europe in an unpredictable fashion.

Though the week-long event has run smoothly, it has not been without incident; the European Broadcasting Union expelled the Chinese broadcaster from the event after it censored two performances in the first semi-final.

Mall, performed by Albania's Eugent Bushpepa, was cut because it featured performers with tattoos and Together, performed by Ireland's Ryan O'Shaughnessy, featured lyrics and visual imagery about a same-sex relationship.

The Chinese broadcaster Mango TV could not give the EBU an assurance that the performances, both of which booked slots in the grand final, would not be censored again so the EBU tore up its broadcasting agreement.

"[The censoring of the two performances] is not in line with the EBU’s values of universality and inclusivity and our proud tradition of celebrating diversity through music," the EBU said in a statement.

It is also, somewhat controversially, the first time since the introduction of the semi-finals in 2004 that Azerbaijan, Romania and Russia failed to qualify for the grand final.

The six-decade-old song competition has served as the launchpad for a string of high-profile artists, notably ABBA, who won in 1974 with Waterloo, Celine Dion, who won with Ne Partez Pas Sans Moi in 1988 and Brotherhood of Man, who won in 1976 with Save All Your Kisses For Me.

The grand final of the 63rd annual Eurovision Song Contest will air tonight at 7.30pm on SBS; the two semi-finals and grand final can be replayed via SBS On Demand.

The journalist travelled to Lisbon courtesy of SBS.