Chiwetel Ejiofor immersed himself in the history of the 1930s for his role in new TV drama Dancing On The Edge.
The actor plays Louis Lester, leader of an all-black band made up of British and American musicians, in the BBC Two drama.
Acclaimed writer and director Stephen Poliakoff's drama is set in 1930s Britain and deals with immigration, racism and class.
The Salt actor said: "Most of all it was about trying to understand the period.
"Particularly as people nowadays are not really aware of the issues that people had to deal with during this time.
"Collectively as a group, the more we looked at the 1930s, the more we realised that there was enormous crossover between what people dealt with then and what we deal with in our contemporary lives."
:: Dancing On The Edge starts on BBC Two on Monday, February 4.