McLaren's official test and reserve driver Lando Norris has been the centre of attention from three Formula 1 teams keen to recruit him, according to the team's CEO Zak Brown.
Earlier this month it emerged that Toro Rosso had made an approach for the 18-year-old's services as a potential replacement for Brendon Hartley.
McLaren turned that down because it would have tied up Norris beyond the end of the current season. The team wants first refusal on Norris for 2019 in case Fernando Alonso decides to retire from Formula 1 in the wake of his Le Mans victory.
However, at the time Brown said that he wasn't against Norris gaining F1 experience with another team - if the terms were right.
"If there was an opportunity for Lando to gain experience then that’s something we would consider," the McLaren boss had said last week in Montreal.
This week Brown has revealed that it's not just Toro Rosso who have been enquiring about just what those right terms might be.
"We've been approached by more than one team," Brown told Autosport. "We've had three approaches, of varying degrees.
"Some included this year, but we want him to focus on F2, and keep him at McLaren.
"If we felt it was good for his career, and good for McLaren, then we'd consider it on a case by case basis," he continued.
"But all of the approaches meant he would have gone away, and we're not interested in that conversation. That's non-negotiable.
"We're not going to train him up for someone else," he insisted. "But I don't think anyone else has any interest in training him up for us."
Red Bull and Ferrari both have junior teams where they can place junior drivers for a rookie season or two in the sport before promoting them to the main team.
Mercedes lacks a junior team but has made deals with its engine customer teams to develop talent from the Mercedes young driver programme such as Esteban Ocon and Pascal Wehrlein.
McLaren doesn't have that ability and has had problems with young talent queueing for a race seat that might never materialise. Stoffel Vandoorne spent a year in Japanese Super Formula before getting his full-time F1 break.
Brown admitted that the situation wasn't ideal.
"We don't have any sister teams," he said. "I think it shows that the FIA needs to look closely into how much influence teams have over other teams.
"What they're starting to do is to close down opportunities for people that are independent."