The Sunday Mirror printed pictures of the 53-year-old BBC political editor kissing a women (not his wife) on Saturday night by a fence outside a bar in Fitzrovia.
He has since claimed the embrace was a drunken farewell with a colleague, and said his wife of 25 years was "very cross" with him.
"I am a grown-up and I should know better", said Marr. "It was very poor behaviour on my part and she is entirely right to be annoyed."
Last year Marr admitted having an affair with a fellow journalist, and revealed he had won an injunction in 2008 to cover up the scandal.
Speaking of his booze-fuelled antics this weekend, he said:
‘It had been a long drunken evening and it was just a silly thing. It was just two drunken journalists having a farewell clinch after working fantastically hard together for two years. There is no romantic connection between us. There never has been and never will be."
Fantastically hard indeed.