King Charles III returns to London to continue treatment for cancer that the Palace keeps secret. Charles, 75, and his wife, Queen Camilla, arrived by helicopter at Buckingham Palace from their Sandringham estate.

The crown did not reveal what type of cancer he suffers from, although it noted that it was not related to the recent treatment he received for a benign prostate problem. Charles announced last week that he would postpone all public duties while he undergoes treatment for an unspecified cancer, discovered while receiving treatment for his benign enlarged prostate.