Chris Evans is to step down as the main presenter of Top Gear after just one series, following disastrous ratings. Evans, one of a number of hosts including Matt LeBlanc in the new format of the motoring show, said he will stand down after "giving my best shot".

The latest episode of Top Gear attracted just over 1.9m viewers, a drop of nearly 50% from the first episode of the series' 4.3m.

Evans said via Twitter: "Stepping down from Top Gear. Gave it my best shot but sometimes that's not enough. The team are beyond brilliant, I wish them all the best. Full steam ahead then with Radio 2, CarFest, Children In Need, 500 Words and whatever else we can dream up in the future."

In a full statement, Evans added: "I have never worked with a more committed and driven team than the team I have worked with over the last twelve months. I feel like my standing aside is the single best thing I can now do to help the cause. I remain a huge fan of the show, always have been, always will be. I will continue to focus on my radio show and the allied events that it encompasses."

Mark Linsey, director, BBC Studios on Top Gear, said: "Chris is stepping down from his duties on Top Gear. He says he gave it his best shot doing everything he could to make the show a success. He firmly believes that the right people remain, on both the production team and presenting team to take the show forward and make it the hit we want it to be. The new series has so far notched up over 30m views in the UK alone and has already been sold to 130 territories worldwide."

chris evans
Chris Evans will leave Top Gear after just one seriesGetty

The announcement arrives as Evans is facing a sexual assault investigation following allegations he grabbed a female colleague's breasts in the 1990s.

A Met Police spokesperson said: "An allegation of non-recent sexual assault was made to police on May 23. The allegation was made by a woman against a man, and relates to incidents in Tower Hamlets in the 1990s. There have been no arrests and no person has been interviewed under caution."

Evans was the host of Channel 4's The Big Breakfast in the early 1990s, which was filmed in the Tower Hamlets area of London.

Evans was named the main presenter of the latest series of Top Gear after the BBC did not renew previous presenter Jeremy Clarkson's contract after he was suspended for punching a producer. Clarkson's co-presenters James May and Richard Hammond left soon after, believing the show could not continue without Clarkson.