Hamilton has long had a "gentleman's agreement" with the Japanese company, who supply free helmets and service to F1 drivers, but have a policy of not paying them a fee on top.

Despite his Arai history, Hamilton has been experimenting with a Bell in testing and practice sessions this year.

However, Bahrain was the first time he used one in qualifying and the race.

Drivers usually take into account the aerodynamic properties of helmets – they are part of the complex interaction between the windscreen and the airbox – and Hamilton suggested in Bahrain that was important when asked if comfort, aerodynamics or a commercial arrangement influenced his thinking.

"It's not something I'm willing to talk about at the moment," he said when asked by Motorsport.com after he used a Bell in qualifying.

"Because I haven't made any decisions. I was just trying... As a driver you want to improve everywhere, and the [Arai] helmet's not been in the wind tunnel.

"I've had Schuberth trying to get me to try their helmet as well. Ultimately you all know I've been with Arai since I was 10-years-old, a long, long, long time, but they don't develop as Schuberth and the others do, and I like that, I like helmets that are developing and improving.

"That doesn't mean that Arai... Arai's still a damn good helmet and I've been with them a long time, and you see me swapping back, because I always go back to the old reliable."

However, the following day he opted to use the Bell in the race.

Tipping point for Arai

Sources suggest that Arai's Japanese management regard that decision as a tipping point, and that the company can no longer support Hamilton.

In addition, his comments about lack of development did not go down well. One source said: "The 'undeveloped' helmet won the last five world championships..."

The Bell Racing Europe F1 operation now has strong Bahraini links and has recently opened a new facility adjacent to the Sakhir track, so getting a big name like Hamilton on board is clearly good business.

However, the company's management could not confirm that it has a new formal arrangement with the world champion.

However the company's Facebook page left little to the imagination when it noted: "Fabulous results for our Bell drivers Lewis Hamilton and Kimi Raikkonen at Bahrain GP 2015."