Richard Hammond’s brainbox has been so bashed about in car crashes that he has a ­memory like a sieve, according to ­co-star Jeremy Clarkson.

Hamster’s fellow presenter on The Grand Tour ­complained: “You can tell him something and five seconds later it is gone out of his head.

“Well, it is not his fault, it is because he cannot drive and he went upside down and damaged his brain.

"He has no capacity for remembering anything and some of it is because he is not interested in anything and some of it is because he has had brain damage.”

Hammond, nicknamed the Hamster, suffered life-threatening head injuries and brain damage 11 years ago.

(Image: Ellis O'Brien)

He was in a coma for a fortnight after a 288mph crash as he filmed a stunt for BBC’s Top Gear.

Then, filming The Grand Tour last year, he lost control of a supercar in Switzerland that flipped over and burst into flames.

(Image: Ellis O'Brien)

He escaped with a fractured knee and is back in the new series of the Amazon show.

Surprisingly, he is still happy to do stunts – but less surprisingly he was knocked out after falling off a ­motorbike filming the Mozambique special.

Hammond, 48, said: “Basically, what’s gone wrong is I keep getting injured.”

(Image: Ellis O'Brien)

Clarkson, 57, said they struggled to contain their laughter while shooting.

He said: “There are moments where I laughed so much, you know that dangerous laughter when you think, ‘If I do not breathe in I’ll suffocate.’”

(Image: Ellis O'Brien)

The Grand Tour Mozambique Special will be available on Amazon Prime Video on February 16.

■ TOP Gear presenters Chris Harris and Eddie Jordan avoided injury when a car they were driving burst into flames during filming in Monaco this week.