Fernando Alonso's failure to qualify for the Indy 500 was not part of the script McLaren had planned to write for the two-time world champion this year.

Far from it, in fact. When Alonso was doing doughnuts at the end of his Formula One swansong, the Abu Dhabi Grand Prix this past November, McLaren CEO Zak Brown opened up his radio channel to say: "Let's go win the Triple Crown together!"

That declaration has not aged well -- on Sunday, Alonso and McLaren failed to even make the grid for next Sunday's race. That outcome is embarrassing for both -- worse still, the reasons behind that failure can be traced back to what was happening in Formula One the last time Alonso competed in an orange car at the race known as the Greatest Spectacle in Racing.

The McLaren-Honda split

Fernando Alonso sitting on a deckchair after a car failure in Brazil became an iconic image of the McLaren-Honda era. Peter J Fox/Getty Images

McLaren's F1 partnership with Honda was supposed to last for 10 years and propel the team back to the front of the Formula One grid. It started on the back foot in 2015 and never recovered -- the team's horrible 2017 campaign, which included a Honda-made engine failing in Alonso's car in the closing stages of his impressive Indy 500 debut, saw the relationship reach its breaking point. The deal was cut short, with the team taking on a customer Renault deal instead.

McLaren repeatedly laid all its failures of the previous three years at the feet of Honda, claiming the Japanese manufacturer had hindered what it labelled to be the best car on the grid. Alonso -- who was rumoured to have demanded the end of the partnership as a prerequisite for staying in 2018 -- boastfully declared "Now we can fight!" after finishing sixth at the opening race in Australia.

McLaren's brash and arrogant attitude to the new engine soon began to crumble -- as results tailed off, Eric Boullier was ousted as racing director. That prompted a reshuffle that brought Gil de Ferran, Alonso's 2017 Indy 500 mentor, on board as sporting director and the Spaniard's long-time race engineer Andrea Stella as performance director.

Despite those changes being made to promote those closely affiliated with him, Alonso's patience had run out by the summer and in August he announced he was stepping away from F1 racing duty. Brown has left the door open for the two-time world champion to return in future, leaving Alonso the chance to contest Indy on his own terms.

Alonso wins at Le Mans

Accelerating Alonso's decision to quit F1 and return to Indianapolis was his drive to victory at the Le Mans 24 Hours in June 2018 with Toyota teammates Kazuki Nakajima and Sebastien Buemi. The Spaniard competed in the race as part of the World Endurance Championship super-season, which McLaren granted him full blessing to participate in.

Porsche's departure from the series had made a victory in the event seem much more likely -- Alonso helped propel his No.8 team to the win with a remarkable overnight stint that dragged them back into contention when it looked as if the No.7 Toyota would end the famous endurance race first. After the win, Alonso signaled his desire to complete the Triple Crown -- it then became a matter of who he could compete in another Indy 500 with.

McLaren returns to the 500

Brown spent much of 2018 weighing up how much to commit to IndyCar in 2019. McLaren approached two former IndyCar champions, Scott Dixon and Will Power, about potentially driving for its team if it were to enter for a full season.

Eventually, it opted against doing so -- ahead of the U.S. Grand Prix, Brown confirmed the team would not contest the full IndyCar season in 2019. Its decision to participate in the Indy 500 with Alonso was confirmed a month later, albeit without any details about technical partnerships or engine supply. Unlike 2017, it was a full McLaren entry, and Brown was quick to play up the significance of his team's return -- Johnny Rutherford won two Indy 500s with McLaren in the 1970s.

Fernando Alonso moved a step closer to the Triple Crown with victory at Le Mans. James Moy Photography/Getty Images

Enter Chevrolet

The collapse of McLaren's relationship with Honda had an adverse impact on its preparations for this year's Indy 500. In 2017, McLaren had been able to enter a close partnership with the Honda-powered Andretti Autosport team. Unlike 2019, this was not a full McLaren entry, but the British team was able to lean extensively on Michael Andretti's team and its knowledge of the famous oval race -- it had won in 2016 with Alexander Rossi. It remained competitive throughout 2017 and, despite a string of Honda engine failures, would win again with another of Alonso's teammates for the weekend, Japanese driver Takuma Sato.

Had things been handled differently, Honda might well have agreed to partner with McLaren at the Brickyard. Instead, McLaren had repeatedly thrown its partner under a bus -- although Honda's F1 and IndyCar operations are vastly different, it had no interest in doing a deal for Alonso and McLaren, leaving Chevrolet as the only option on the table. The American manufacturer had won three of the past six races at the Brickyard, but that deal limited the number of teams McLaren would be able to work with on its return to Indy.

Fernando Alonso will not compete in this year's Indy 500 after failing to qualify. AP Photo/Michael Conroy

Carlin tie-up

A deal with Andretti Autosport had looked to be the most logical, given the pairing's success in 2017, but with the Honda bridge well and truly burned, that was no longer an option. McLaren eventually settled for something slightly different from what Alonso had for his debut -- what it called a "strategic alliance" with British team Carlin, an outfit with a string of success in junior categories and in the Indy Lights feeder series but in only its second year on the IndyCar grid.

There was sense to the partnership in the circumstances. McLaren prodigy Lando Norris raced for Trevor Carlin's team in European Formula 3 and Formula 2 before his elevation to F1 this year. The nature of the alliance also meant Brown could stay true to his desire of 2019 being a proper McLaren entry. With Former Force India deputy Bob Fernley already in place as head of the Indy 500 team, McLaren was committing more resources and manpower towards winning the race than it had needed to in 2017.

Alonso got the chance to sample IndyCar's new, simplified aero package during a test at the Texas Motor Speedway earlier this year. He admitted the new cars were more challenging to drive and said: "This year I am not with the Andretti environment. It's all by ourselves this year".

Indy struggles and a crash in free practice

Alonso's preparations for the race were far from ideal. Scatters of rain delayed his running in the 'rookies and refreshers' test at the beginning of May, limiting him to just 29 laps. That was in stark contrast to his preparations two years ago, where he was given the chance to test privately before those same events took place. While in 2017 he looked like a contender from the moment his engine was fired up, he looked to be on the back foot as soon as he arrived this year.

During the opening week of the race, Alonso crashed heavily after losing control of his car while following a rival, costing him all of Thursday's running as McLaren frantically built a spare.

Brown admitted the McLaren team that had been specially built for this Indy 500 was not as efficient as it could have been.

"Being a new team is certainly a disadvantage as it takes time," Brown is quoted as saying by Autosport. "The guys are all very experienced, but they've not worked together as a team before.

"So this is the first time they've had to rebuild a car overnight, and you're always going to do it a second time or third time or fourth time. The only way to get through that is to be a new team once, learn from it. But they're cool, calm and collected."

During the initial qualifying, Alonso's four-lap average was just 0.020mph slower than Pippa Mann in 30th, forcing him into the six-car shootout to determine the back row of the grid.

Alonso gets bumped on Bump Day

Until the final run, Alonso was set to start from 33rd -- the final slot on the grid -- until relatively unknown American driver Kyle Kaiser beat the two-time world champion by 0.019mph at the death. It was a huge giant killing -- Kaiser's Juncos team had arrived in Indianapolis with a plain white car after two major sponsors pulled out on the eve of the race yet was able to claim the scalp of two of motor racing's most famous names.

As soon as McLaren turned down the opportunity to buy another team's entry to ensure Alonso lined up in the race, the Triple Crown dream was officially dead for another year.