The 61-year-old guitarist was seen out with friends, including snooker star Ronnie Sullivan and artist Damien Hirst, only days after leaving Surrey's Life Works rehab clinic, where he was being treated for drink, sex and drug addictions.
A friend close to Jo, 53, said: "To say she has her suspicions about his drinking would be an understatement. Nothing surprises her with Ron any more."
"He's moved back from rehab and his family are sure he is back on the vodka. They know him better than anyone else."
"One of his sons was told Ron had been spotted drinking neat vodka again."
"Jo knows better than anyone that he is an expert at keeping his drinking under the radar."
Jo previously vowed to refuse to speak to Ronnie until he was drink-free, though she did visit him towards the end of his stint in rehab.
Others who attended the party with Ronnie at London's exclusive Claridge's restaurant insist he didn't have a drink on the night, sticking to coffee.
A source told Britain's The Sun newspaper: "Ron played snooker, ate bacon and egg rolls and drank some coffee."
"Ronnie O'Sullivan scored a 145 break and everyone left with a smile on their face. It was all good, clean fun."
"Ronnie has been having sessions three nights a week with an addiction counselor even though he has left rehab and is doing really well."
Ronnie was originally admitted to rehab in July following a ten-day drinking session with now 20-year-old Ekaterina Ivanova, a Russian-born waitress, who he met in a London club.
