Rosen said she worked as a groom for about seven-and-a-half years before leaving after she married.
During their reunion, she said she and the princess recalled people and places from their time at Windsor and looked through old photographs.
They also spoke about three-day eventing, in which the princess later competed.
David Delew, chief executive of Manchester Jewish Community Care, said the meeting was one of the highlights of the Royal visit.
He said Princess Anne spent longer in the centre’s reminiscence room than he had expected as the pair talked about “the old days, the different horses and the family”.