It is called a scam! The woman is absolutely crazy. Her own family, her siblings (the children of Hamilton O'Malley and his second wife, Sadie) acknowledge that she is their sister. She's delusional, has mental issues, and is in need of money. The order of Mountbatten of Carisbrooke ... no such animal!
Grania has no income, and has been trying for years to gain money from Lady Iris Mountbatten's estate. She claims she is Lady Iris's daughter. Even though lawyers have tried to set her straight, she continues with her rants and tirades. The Home Office has been informed that she has lied about the date of birth on her passport - and the true details provided to them.