The movie could be shot only in Great Britain, because the plot was necessary to show a large number of "Aristocratic" locations, castles, palaces, old pubs, parks, a large number of rooms, bibliothèques and grounds. That's why they chose Great Britain for the movie.
Restaurant
In movie
Scene where Lady Elspeth bumps into Oliver at a posh restaurant.
Real
Scene was shot at Launceston Place restaurant in the heart of Kensington, London.
London
Dining room
In movie
Scene where Оливер встречает математического гения Майкла Гэйви
Real
Scene was shot in the dining hall of Brasenose College, University of Oxford.
Oxford
Creek
In movie
Scene where A stone bridge over a stream where family members throw stones into the water
Real
Scene was shot at Dean Park in Corby, Northamptonshire. Which is not part of the grounds of Saltburn Manor. This 14th century country estate is owned by an aristocratic family, but unlike Drayton, it is open to the public.
Saltburn House
In movie
Scene where Oliver Quick stands with a suitcase in front of the gates of Saltburn Manor.
Real
Scene was shot On the Drayton House estate near Lowick in Northamptonshire. Originally built around the 14th century, the house served as the stately residence of the Drayton family and displays impressive Elizabethan architecture characterized by symmetrical design and ornate detailing.
Oxford
In movie
Scene where we're shown Oxford University and the students
Real
Scene was shot in Oxford, next to Radcliffe's Cambra (Radcliffe Camera) - this building houses the academic library. And you can also say, if something is filmed in Oxford, Radcliffe's Cambra will definitely be in the frame. She can be seen in the 2023 movie Wonka, for example.
Oxford
Radcliffe Camera