Britain\'s Queen Elizabeth II\'s first public appearance since being treated for gastroenteritis will be at a Westminster Abbey event Monday, officials said. Prince Philip will accompany the queen to a service and reception and then they will go to another reception at Marlborough House in central London, the BBC reported Friday. Buckingham Palace officials said Elizabeth, 86, also has engagements on her calendar for Wednesday and Thursday. The queen, who was discharged Monday, canceled a weekend visit to Rome. The hospitalization was her first since 2002 when she was treated for a minor knee operation and non-cancerous lesions on her face.