Hamilton key to 2019 driver market, says Horner

Of the top three teams' drivers, only Ferrari's Sebastian Vettel and Red Bull's Max Verstappen have deals that run past 2018 - with championship leader Mercedes yet to confirm either Hamilton or teammate Valtteri Bottas for next year.

Red Bull is working on an extension for Verstappen's teammate Daniel Ricciardo, but also retains Carlos Sainz under contract - and could call him back to its main Red Bull Racing outfit from Renault should Ricciardo depart.

Sat next to Mercedes chief Toto Wolff in a Red Bull Ring press conference, Horner was asked to clarify Sainz’s position, and he made it clear in an aside to the Austrian that Ricciardo’s future is connected to that of Hamilton and, to some degree, Bottas.

“All of these things are interlinked in some way, shape or form,” said Horner. “I think the whole driver market is waiting for Toto’s driver to kick that off.

"I’m hoping Silverstone you’re going to finally get your finger out and sign a contract. He’s worth every penny!

“As soon as Toto signs his contract, or two contracts, that then will cascade, and Carlos Sainz will be a mechanism within that. It’s all down to Toto, really.”

Pressed on Red Bull’s plans for Sainz, Horner said: “I thought I’d successfully managed to swerve that question!

"Look, Renault have a desire to keep Carlos. It really depends on whether we have a requirement for him or not.

"Our intention is to retain both drivers. Once that’s cleared, the we’ll sit down with Carlos.”

Ricciardo is thought to be closing on a Red Bull renewal, and Horner said he is confident the talks will conclude before F1's summer break in August.

“Things are progressing well with Daniel. I think things will be concluded prior to the summer break.

"Our priority has been firstly to get the engine situation sorted, and now things are progressing with Daniel.

"I’m sure in the next couple of weeks hopefully we’ll be entering the finishing straight to get things concluded prior to the summer break.”