Mercedes Team Principal Toto Wolff says that 2019 was “a difficult year” despite its championship triumphs due to the “overwhelming” significance of the death of Niki Lauda.

The Mercedes-AMG F1 Team racked up a sixth consecutive drivers’ and constructors’ championship double, with Lewis Hamilton and Valtteri Bottas making for a one-two in the former standings.

However, the year also saw the passing of Lauda, the team’s non-executive chairman since 2013, in May, prompting Wolff to declare that Mercedes had “lost a guiding light”.

Speaking in a Mercedes end of season review, Wolff said that the sadness of the Austrian’s death outweighed the joy of dominating Formula 1 on the race track in 2019.

“2019 will be remembered as a difficult year,” Wolff reflected.

“You can say that the team has achieved a sixth consecutive championship, which was never done before, but for me personally, and many in the team, Niki passing is just the overwhelming event of the season.

“Niki was very ill from the summer (of) 2018 but then dying is something that really affected us badly.

“Still today I think about him every day and it feels surreal that he’s not part of the team anymore, so 2019 for us will be the year that we have lost Niki.”

Expanding on his relationship with Lauda, Wolff described the three-time world champion as someone who had become an extremely close friend during their time working together.

“Niki and I, we really grew together over the many seasons and at the end he was probably my closest confidante, friend, and sparring partner,” recalled Wolff.

“So, I missed the protocol of travelling to the races together, having him as a sounding board, and then somehow a safe place to talk about things that are out of the team.

“So, there wasn’t a single event where I said I missed him, it’s just that the friend is not there anymore and this obviously has a big impact on us.”

Mercedes switched its halos from silver to red, the colour of Lauda’s famous cap, for qualifying day and the race at the Monaco Grand Prix which took place in the days following his death.

It also changed one of the three-pointed stars on its engine covers to red, a feature which Wolff advised at the time “is going to stay on the car forever”.

Lauda was posthumously awarded the personality of the year honour at the FIA prize gala earlier this month.