I agree. He has incredible talent and, for me, he is the standout of the film, among a whole cast of stellar performances. He is pure class and an Oscar has his name on it in the near future I’m sure.
As an Irishman we are so used to nobody doing our accent(s) well, ever! We actually kinda like it. We like pointing out how bad they are. Speaking for myself, and everyone I know who saw the film- I believed he was Irish. Never even questioned it once. I was stunned when I heard him speak without it. Stellar performance, in the midst of stellar performances.
Just recently found this movie via an interview with Andrew Scott on RU-vid. Amazing story and wonderful film which deserves more attention - go watch it!