Alexander Wingfield spent about two hours immediately before the fatal crash in Paris with Mr Paul, 41, whose post-mortem blood tests proved he was more than three times over the drink-driving limit.
Mr Wingfield has told BBC1's Panorama: "I never saw the guy drink anything. I mean he was French, he'd been off duty. The French drink wine at every meal, but there was nothing in his demeanour that would suggest to me that he was drunk.
"He was exactly the same as he was in the afternoon, just a nice guy and he was sober."
In a programme, entitled Diana, The Last Day, to be screened tonight, Mr Wingfield said of the accident: "If anyone is to blame it should be whoever was hounding the car that night because there had been an escalation throughout the whole period we were away."
He said that, ironically, Diana had been concerned for the safety of the photographers earlier in the day. She feared they might fall in front of the cars.Reuse content