Red Bull and Mercedes were involved in a multi-million pound High Court battle over the release of some of Mercedes’ engineers to their bitter rivals, Christian Horner revealed on Friday.

Speaking to Telegraph Sport ahead of this weekend’s Emilia Romagna Grand Prix, the Red Bull team principal scoffed at claims last year from opposite number Toto Wolff that the defection of a number of personnel from Mercedes’ engine facility in Brixworth to Red Bull’s new powertrain facility in Milton Keynes would not have an effect on performance.

“I mean, we’ve spent a million quid in the High Court fighting for a couple of them,” he said. “You don’t do that for the ones you want to lose. That [£1million] is what it would have cost them [Mercedes].”

“You’re not telling me that you take out the head of mechanical design, the head of their energy recovery system, the head of manufacturing… that that doesn’t have an effect?”

Horner also pointed to the departure of Andy Cowell, the ex-managing director at Mercedes AMG High Performance Powertrains, who left Brixworth at the end of 2020, although not to Red Bull. “That has to have an effect,” he said. “Already last year it was starting to have an impact. They [Mercedes’ engines] weren’t as competitive as they had been in previous years.”

Mercedes did not provide an official comment. Both teams confirmed earlier this year that they had reached a settlement over Ben Hodgkinson, who had been head of mechanical engineering at Mercedes’ High Performance Powertrains since 2017, having worked at the German manufacturer’s Brixworth headquarters for 20 years. Hodgkinson will join Red Bull next month as the new technical director of their powertrains division.

Mercedes’s major concerns right now are not with their engine but with their chassis. Lewis Hamilton’s team endured another disastrous day on Friday, the seven-time world champion qualifying 13th for Saturday’s ‘sprint’ race in Imola, two places behind team mate George Russell.

In treacherous conditions, which caused a record five red flags, Red Bull’s world champion Max Verstappen took pole ahead of Ferrari’s championship leader Charles Leclerc. McLaren’s Lando Norris will line up third on the grid.

Chrisian Horner interview: ‘I slept with Toto…on the plane back from Australia’

Christian Horner is in an unusually diplomatic mood. Red Bull’s team principal, normally so mischievous, spends much of our interview on a rainy day in Imola saying how competitive Mercedes are and how “foolish” it would be to write them off despite their current travails. Ferrari, meanwhile, “have not shown any obvious weaknesses” this season and have done “an excellent job” with the new regulations and with their engine. It is, he says, a real concern.

Surely there must be some juicy gossip to impart? Is there no cheating row coming down the track? No scandal brewing? What will the Netflix generation, weaned on a diet of controversy and intrigue, have to talk about? Horner thinks for a moment. “I slept with Toto for the first time,” he offers. Before Red Bull’s attendant press officer can splutter into his cappuccino, he swiftly adds: “On the plane on the way back from Australia.”

There are some who find Horner irritating; constantly moaning when things go wrong for Red Bull, too readily available to Sky Sports or Netflix. But he has always been good company; capable of poking fun at himself. And whether you enjoy his style or not, he is an excellent team principal.