[5] Critics responded with fulsome praise for his performance: "Mr Valk works in the grandest continental manner...every gesture breathes intelligence and every vocal note is true".

"[7] Valk never received top-billing in films, but was happy to accept supporting roles in good screen productions.

High-profile films in which he featured include The Young Mr. Pitt and Thunder Rock (both 1942); Dead of Night (1945); A Matter of Life and Death (1946); Mrs. Fitzherbert (1947); The Magic Box (1951);[8] and The Colditz Story (1955).

[9] Aged 61, Valk died suddenly in London on 23 July 1956 during the run of the play Romanoff and Juliet in which he was appearing.

His wife Diana subsequently wrote a memoir entitled Shylock for a Summer in which she revealed that Valk had been planning to write an autobiography at the time of his death, and had written a note to himself stating: "I don't want to talk at length of my histrionic adventures – the idea of this is to draw a curve of a life, lived in shadow and sun but lived with gratefulness.