But these exclusive pictures will be a fresh blow to the singer, who announced her split from Joshua just days ago.
The break-up came amid claims actor Joshua, 29, had become close to a Spanish co-star while filming a romantic comedy.
The pictures of him in a clinch with another woman raise further suspicions.
Mirror can reveal Joshua enjoyed a three-hour lunch in a pub with the pretty brunette.
One onlooker said of the West London rendezvous: “They seemed very happy in each other’s company. You could tell they were close and had a lot in common.
“They were laughing a lot. If you didn’t know Joshua was with Kylie you might have thought they were a couple.”
By the time they left it was dark and the woman followed Joshua to his motorbike before heading off into the night.
The onlooker added: “The lady gave Joshua an embrace and they seemed close. They were clearly very fond of each other.”
It is not known if Kylie, 48, knew about Joshua’s friendship with the woman. But a source claims her increasing suspicions about his loyalty led to the end of their 18-month romance.
The source believes the singer felt she could “no longer trust” Joshua after he had grown close to his TV co-star Marta Milans, 34.
It has been suggested they bonded in Vancouver, Canada, while filming the rom com No Tomorrow.
Kylie confirmed the split on Instagram with an emotive image of a sunrise over calm waters.
Using the hashtag #thesunalwaysrises, she captioned the picture: “We wish only the best for each other as we venture towards new horizons.”