Alonso had run strongly in the first part of the race, before making a late pitstop.

He looked destined for 10th place until he was forced to stop at the hairpin, where he subsequently paid an impromptu visit to the grandstands.

The Spaniard also now looks set to take grid penalties for the next race in Baku, as any change of turbo or MGU-H from now on is beyond the allocation of four. Jenson Button took the first raft of penalties for his car in Monaco.

The late Montreal retirement was yet another blow to McLaren's increasingly shaky relationship with its engine partner.

"Fernando did a world champion job again, and the engine let him down again," Brown told Motorsport.com.

"It's a bit of the same old story, which is something that needs to get fixed one way or another. Because we can't keep doing this.

"I think he was clearly going to get our first – not even points – but point. It was good to see Stoffel make it to the finish. But I'm just speechless.

"You feel like you're finally going to get your first point of the year, and a couple of laps from the end, it goes. Just really poor power, and really poor reliability."

Brown agreed that heading to the next race in Baku already knowing that Alonso will be penalised was a frustrating prospect.

"It's pretty depressing for all of us. Starting at the back before you even get the weekend started, is not how we can go racing.

"All we can keep doing is pushing for developments. Nothing changes today – it just increases the frustration. But as we've said, we've got to get our act together, and it's one more race that we didn't."

Asked if the McLaren management's recent criticism of Honda was intended to send a message to the Japanese manufacturer's board he said: "I think it was important that we spoke up this weekend, it was really the first time that McLaren brought forward their views.

"I don't want to repeat ourselves, and I don't think this changes anything, it just reinforces our position.

"I think they know something needs to be done. They are frustrated, they are upset. I think today 400 million people saw what happened, so I don't think we need to communicate already further than we already have.

"I don't know what the [Honda] board thinks, but I think everyone thinks the same thing, just work hard to try and fix it. But right now, it's not fixed."

Brown continues to suggest that the summer break is the deadline for a decision on 2018 plans: "There or thereabouts. We'll see where we are then."