Kimberly Stuart (Rod Stuart’s offspring) popped in to see John when he was playing at this Sunday’s Hard Rock Calling gig in Hyde Park. The pair, who know each other from the LA club scene, were talking backstage when Jen spotted them and got a case of the green-eyed monster, and immediately ordered Kimberly to be removed from the backstage area.

But one warning wasn’t enough for Kimberly. Ten minutes later, she was on the side of the stage, waving at John and cheekily catching Jennifer's eye while she was taking photos of her boyfriend. Angry Jen didn’t like this very much, as you can imagine. A close source revealed:

"Kim was pulled off the stage and escorted through the Hard Rock VIP tent with a face like thunder, shouting: 'Why doesn't he want me here? Is this because of her?' "She totally embarrassed herself, but Jen looked relieved."

There’s no telling some people, is there??