Mills McCartney, 38, said nothing as she arrived at the neo-gothic courthouse for the closed-door session. The former Beatle arrived at the court's back door soon after.
McCartney whistled and snapped his fingers as he left the building after the two-hour hearing, flashing a peace sign to photographers stationed outside the court's parking lot before being driven off in a waiting car.
Mills McCartney left the courtroom through a back door about half an hour later.
The former model, 38, and the 64-year-old musician separated last May after four years of marriage and began divorce proceedings in July. They have a 3-year-old daughter, Beatrice.
British law forbids publishing details of allegations in divorce cases. Mills McCartney began legal action against a number of media outlets after disparaging claims about her husband, alleged to have been contained in divorce court papers drawn up on her behalf, were reported in the press.