In truth, when Brendon Hartley was revealed as the replacement for Pierre Gasly, who was in turn replacing Daniil Kvyat, at the 2017 United States Grand Prix, more than a few eyebrows were raised.

Test and reserve driver for the Faenza team and its sister outfit in 2010, alongside Daniel Ricciardo, Hartley had been unceremoniously dumped less than halfway through the season after it was deemed his performances in the Formula Renault 3.5 Series weren't good enough.

Subsequently snapped up by Mercedes as test driver for its F1 team, the kiwi went on to join the newly-formed Porsche WEC team with which he was to win two WEC titles and the Le Mans 24 Hours.

The first to admit to being shocked at getting the Toro Rosso - despite making the call to Helmut Marko in the first place - when retained as Gasly's teammate for 2018, Hartley thought he'd finally made it.

Out-qualifying his teammate in Melbourne got Hartley's season off to a good start, but next day he could only manage a distant 15th.

Bahrain, however, was altogether different.

"Bahrain was my biggest missed opportunity," he admits to the official F1 website, "and a hard one to swallow as we had a such a competitive car that weekend (which was somewhat of a surprise at the time).

"I had the pace to comfortably finish well into the points, and my team mate, Pierre, had a faultless weekend, taking his best result of the year.

"There wasn't much between me and Pierre in qualifying. But I had contact with another car on the first lap, drawing a penalty, which removed a chance for a big points haul. I left Bahrain knowing I had missed an opportunity to score my first F1 points. And knowing I couldn't afford to miss many of those. I knew I had to be better."

Indeed, for while the kiwi finished 17th, a lap down on race-winner Sebastian Vettel, teammate Gasly finished an amazing fourth, the Faenza team's best result in many seasons.

Though his first point was finally scored in Azerbaijan, by the time Hartley arrived in Monaco there were increasing rumours that Toro Rosso had already made a bid to secure the services of Lando Norris, aiming to slot the McLaren protege into the second car alongside Gasly.

"Sarah (his wife) and I actually have a good view of the circuit from our apartment and it's always one of our favourite weekends of the year," he admits. "But for me, it was tough, because when I look back now, what I will remember most about it is walking down to the paddock to meet with the media on the Wednesday before the weekend started, and receiving a bunch of questions about my future.

"Here I am, a handful of races into my F1 career, and I'm being asked about the end.

"The worst part of that day, though, was finding out there was some truth to the rumours. After a few races, there were some people, it appeared, who didn't want me there. I'll be honest, this was a bit of a shock. After entering F1 with a wealth of experience, two World Endurance championships, a win at Le Mans, and out qualifying my team mate two out of the first three races, it was hard to for me to believe that there was talk of my being replaced so early.

"That's life in F1, though. The sport has so much money and so many people involved, it's only natural that there are politics. If you're a fan you know it, and if you're a driver, you live it."

Though he doesn't name names in terms of who was seeking to oust him, Hartley is keen to point out the loyalty of the majority of the Toro Rosso crew.

"I always, always, had the support of my guys in the garage," he insists. "The mechanics, engineers and everyone in Toro Rosso dedicate so much of their life working many hours to give the team and the driver the most competitive car they can, week in and week out. There's more than 500 staff at Toro Rosso - so it's no surprise F1 is very much a team sport.

"I walked back to our apartment that night looking at the walls of the Monte Carlo circuit, knowing that, if I binned it, if I made contact with those walls this weekend, my F1 career might end in a few days. I knew every practice session carried more weight for me. Every lap time, every result was going to be under scrutiny and could be used against me to leverage my seat.

"That's a unique type of pressure that I hadn't quite experienced before. But the way I responded, the way I put my head down and kept going - that's one of the things I'm most proud of this season. I put in some quick sessions heading into the race, but on Sunday I was taken out from behind and ended with nothing to show for the weekend.

"When that happens, you're sort of back at square one. There's no time to pout, because the pressure's intense. That's the fascinating thing about the midfield battle in F1. There's so much made of the title fight, but the teams in the middle, who are literally fighting for their jobs, their careers, that's a different type of intensity, which is not always caught on camera.

"That looking-over-my-shoulder feeling didn't really go away all year. But, that's just how it is. Every driver or athlete at a professional level must deal with pressure, and all will have their own way of handling it or even turning it into a positive. The pressure comes from all angles in F1 but the feeling of being under the microscope all the time, that was the one that I hadn't dealt with to this extent before.

"It felt like if I farted in the car somebody would be writing or commenting on it. I did find myself hardening my approach, being more selfish with my time on race weekends, and caring much less about what was written or what others thought. I was there to do a job on race weekends, but reminding myself to enjoy it was something I did often. And believe me, there is a lot to enjoy inside an F1 car."

"I will miss it. I'd be lying if I said otherwise," he says of F1. "But I'm excited for whatever is next. I am working to put all the pieces into place for 2019 and beyond. I'm fortunate to have a few options in front of me, but I need make sure it's a fit. I want something that will continue to challenge me, push me, and make me and those closest to me happy.

"The F1 door is definitely not closed and the experience gained from a year at the top of the sport means I will arrive more prepared and stronger for whatever opportunities come next."