Before they hit it rich with the Carry On films the productions of Peter Rogers and Gerald Thomas had moved sufficiently up market to avail themselves of the services of cameraman Otto Heller and actors John Mills, Roland Culver and Mervyn Johns to make this adaptation of the thriller by Francis Durbridge.
Wilfred Hyde White - who later played the scene with the daffodil in 'Carry On Nurse' - plays yet another unctuous authority figure while - playing straight for a change - Lionel Jeffries observes how rarely you travel as a sightseer on the barges along the Thames when you actually live there; amply compensated for by the use of upmarket London locations like the Royal Festival Hall.
Wilfred Hyde White - who later played the scene with the daffodil in 'Carry On Nurse' - plays yet another unctuous authority figure while - playing straight for a change - Lionel Jeffries observes how rarely you travel as a sightseer on the barges along the Thames when you actually live there; amply compensated for by the use of upmarket London locations like the Royal Festival Hall.