By Abigail O’Leary Prince Harry was reportedly cheerful on his return flight to the US after seeing his father King Charles following his cancer diagnosis. The Duke, 39, flew to the UK last week where he is said to have spent around 24 hours – with an overnight stay at a hotel. It has been reported King Charles, 75, personally told Harry and William about his diagnosis before Buckingham Palace made the public announcement. At the time, Harry was in Montecito, California, where he lives with wife Meghan and their two children. After jetting to the UK for a flying visit to see the King, Harry re…