The couple, who split last fall, were reportedly together again at a private members club in Chelsea on Saturday night. Chelsy, 25, had jetted back into London from southern Africa on Friday and was also seen shopping in the city's trendy King's Road.
British tabloid The Sun alleges the couple climbed into the trunk of a Jaguar to make a discreet getaway at 4 a.m. – the "clearest signal" that they are back together.
If so, it would be just in time for an invite to the wedding of Prince William and Kate Middleton in April.
Harry's office at the palace would not comment.