Former Toro Rosso racer Jean-Eric Vergne has revealed why Red Bull took a pass on his services for 2015 against his expectations.
In the summer of 2014, Vergne was told that his seat at the Faenza-based junior squad would be filled the following year by teenager Max Verstappen.
But Sebastian Vettel's shock decision to leave Red Bull for Ferrari provided an unexpected opening for the Frenchman at the senior bull outfit.
Ultimately however, Helmut Marko chose Daniil Kvyat over Vergne to race alongside Daniel Ricciardo at Red Bull for 2015.
"In the summer I got a call from Red Bull saying that they would put Max in the car. Back then, I totally understood it," Vergne told Crash.net.
"It was like, okay, Toro Rosso is some kind of school for the Red Bull junior drivers and there was no place to go to Red Bull, so actually it was kind of them to let me know so early in the season.
"But during that call, I said: 'What if Vettel goes?'. He said: 'You will be in the car'.
"I had done a great season so far, it was good. They knew the deficit I had against Kvyat in the car, talking about the weight [disadvantage].
"Later on, when Vettel left, it was after my good races that I had done. But I found out later that because the way it was said, it would have looked bad that they'd come back on that decision.
"It was a frustrating situation, definitely. Then the whole Toro Rosso team wanted to keep me next to Max, and at the end of the day, it was the same outcome. They would not go back on the decision."
Vergne kept a foot in F1, albeit as a Ferrari test and development driver from 2015 to 2016, but switched his focus to Formula E, racing for Andretti Autosport, DS Virgin Racing and Techeetah, his current team in the all-electric series.