Christian Horner admits Red Bull are still close to Sebastian Vettel amid rumours that the Ferrari man might return to his former team.

Having cut his teeth with Sauber, the German flyer moved to Red Bull’s junior team Toro Rosso in 2007 before stepping up to the major outfit in 2009. Success was instant for the 32-year-old, who claimed four race wins en route to second place in the Formula 1 championship.

That was the forerunner to four years of success, with Vettel winning the title in 2010, 11, 12 and 2013. He secured the chequered flag on 13 occasions during 2013 and looked set to continue his domination until rules changes regarding power units ushered in a new era of success for Mercedes.

Following a fifth-place finish in 2014, Vettel moved to Ferrari but has had to play second fiddle to Lewis Hamilton in recent years. Reports of discontent at the Italian marque continue to do the rounds and, without a win since Belgium last year and way behind Hamilton in the standings, he has been linked with a move away.

Horner has now added fuel to those rumours by suggesting that the Red Bull old boy is part of the fabric of the Milton Keynes-based team. “We have great memories of Sebastian’s time with us,” he told Servus TV. “He is part of our history.

“He won four titles and many, many races together with us, including Red Bull’s first win in Formula 1. We have a special relationship with Sebastian. “Although he is now with Ferrari, he still comes to see the mechanics very often, he knows most of the faces here and is still a friend of the team. He was very happy for us at the Red Bull Ring.”

Vettel is not expected to rally over the second half of the season and can be backed at 67.00 to win this year’s F1 crown.