When Joseph Losey was hospitalized for two weeks during this shoot, Dirk Bogarde continued filming assisted by minute, daily instructions over the phone from Losey's hospital bed. When Losey returned to the set he did not re-shoot any of the script, much to the relief of cast and crew.
Originally planned as a film by a different director, Michael Anderson. It was he who commissioned Harold Pinter to write the script, in 1961. When Anderson dropped out of the project, Joseph Losey took over and insisted that Pinter's script be extensively rewritten. This led to what Losey claimed was their only quarrel in over twenty years of close friendship (but Pinter did do the rewrites).