On television, he became well known for his role as the hero, Will Ladislaw, in the BBC adaptation of George Eliot's Middlemarch.
In 2003, he appeared in the lead role in Charles II: The Power and The Passion.
But Tom Stoppard had also seen Making It Better and decided that Sewell would suit the part of the tutor in his new play, Arcadia, due to open at the National Theatre in the spring of 1993.
The best day of Sewell's life so far was early in December 1992, when he was offered both parts. 'At one ghastly moment it looked as though we couldn't have him,' Gail Stevens says.
Sewell thinks the series gets better after the third episode (this Wednesday). The metaphor would amaze his family and his teachers.
Middlemarch is only one of a long list of books that Sewell did not read at school.
But he was not surprised to hear that they had been so good.
When filming began, he tried not to have high hopes: 'I told myself it would probably fail.
George Eliot likes Will Ladislaw (half-English, half-Polish, ed.
Rugby and Heidelberg) so well that she smothers him; even fans say that Will never came to life.
He only read it when he was told about the part in it for him.
'I took it to the theatre when I was in Making It Better, and I read the first page 18 times,' he says.
He enrolled at the Central School of Speech and Drama in London.