I remember watching a TV series in the 1970's and 1980's, Sapphire and Steel. As a kid, it was very dark to watch and pretty scary. The last episode especially so, because there was no happy ending, it ended very dark.
How performance in this series was brilliant, he very commanding from memory and played the series straight.
He was a great actor, it is shame he did not do more in the UK, and worked in the USA more in later life.