When S7 ended, Foyle was all smiles after his replacement in the police force finally arrived, allowing him to resign and pursue other interests, including a trip to America to carry out his vow to bring Howard Paige to justice. In 2010 Anthony Horowitz said that he very much hoped the next installment of the show could be shot in America to follow the Paige storyline. That would have been awesome in more ways than one (MK on American soil!), but unfortunately, budget limitations precluded filming in the US.
Hoping for a book from AH someday…
@GeraldKelley I have thought about it and it's just possible that I might.—
Anthony Horowitz (@AnthonyHorowitz) January 15, 2016