Conspiracy theorists might have divined, though, that the former actress's assignation with Hugh Grant in Notting Hill had more to it than mere nostalgia.
It had been eight years since the transport minister, who was elected as MP for Hampstead in 1992, was last on a film set. But one thing was for sure, she said. The new mayor would never stray far from the world of luvviedom. The issue of bookings for film crews is such a pressing problem that Labour wants a film commissioner in the new mayor's office to tackle it.
Hugh Grant, who is in Notting Hill making a sequel to Four Weddings and A Funeral, was so honoured that he presented the minister with not one bunch of flowers but two. "I am a great fan," he confessed.
But Ms Jackson - who won an Oscar for her performance in A Touch of Class, shot around Soho and Kensington in the early 1970s - confessed little beyond the fact that she used to do crosswords between takes. "Nothing changes in the film industry," she joked. "You're always waiting around for the technical side to be sorted out."
And the mayor's job? Nothing could be further from her mind. She was simply here to make sure Londoners voted "yes" in Thursday's referendum.