I am a big fan of Bill Nighy's. I have enjoyed him in a series of roles, but this feels to me like his greatest and so different from the more comedic ones he often plays so well. When he "comes alive" in the second half of the movie it is so unexpected and moving.
He really captures the sense of emptiness in the stilted world of 1950s Britain. I grew up in the suburbs of London and was struck by the level of authenticity of the scenes of post war life shown.
I worked in Manchester in the1970s with women much like the three mothers depicted as pushing for a better life for their kids. The bureaucracy was stifling, for example it took many months to get anything repaired in a council owned home. So it was truly heroic for someone to really care. That gave the movie a very hopeful ending.