Brawn had warned last month that he would leave if Lowe arrived and, given that the new man is due to be running the team day-to-day alongside executive director Toto Wolff from next season, it is difficult to envisage how he can continue in his existing role.
Lowe, who has served McLaren for 20 years and the last two as technical director, will not travel to Melbourne for the opening race on March 17. Although Mercedes declined to comment last night it is understood that he will formally join the Brackley team at the end of the year.
Brawn, responding recently to growing questions over his next move, had categorically denied that Lowe would be joining for as long as he was in charge, suggesting he was simply a fallback option: "Paddy is not coming. I want to see how things go before I make a final long-term commitment. If I choose to leave the team then Paddy will come. We have got a plan."
Mercedes non-executive chairman Niki Lauda indicated last night that Brawn had not yet discussed his options after Lowe's appointment. "If Paddy Lowe is coming or not, I cannot tell you now," Lauda said. "Make up your own [mind], whatever you want to do.
"The situation is as it is. McLaren have put him [Lowe] on gardening leave, so let's wait and see. To be clear, Ross has not even been discussed, which is an important thing. But there's peace. Ross is in his position, he will stay in his position, so everything is under control, there is nothing to make out of this."
For McLaren, meanwhile, the loss of Lowe to Mercedes is a clear setback so soon after Hamilton's departure. Lowe will see out his contract in Woking but will almost certainly not be seen around the grand prix scene, with McLaren principal Martin Whitmarsh admitting that he would be performing a "different role" within the organisation. Tim Goss, the engineering director, succeeds him.
On the machinations between McLaren and Mercedes, Damon Hill, the 1996 world champion, said last night: "When Niki Lauda assumed the chairmanship, it was clear that they were going to make some changes, to justify the expenditure that Mercedes are making, and to make a statement."