When confronted with the security breach by the Head of Intelligence and by Phillips' watchdog Jameson, Sebastian tenders his resignation and breaks up with Becky, thinking she was on to him.

[2][3] The Monthly Film Bulletin wrote: "In The Shuttered Room David Greene revealed both a strong visual imagination and a talent for atmospheric scene-setting.

Sebastian confirms that promise, but here again Greene's direction is undercut by a script which toys with an interesting idea and then abandons it for a string of anti-heroic platitudes and a scrappily engineered conclusion.

Characters are introduced and then abruptly abandoned before they have had a chance to establish themselves ... ideas which begin to look interestingly enigmatic soon resolve themselves into spy thriller conventions ...

Nevertheless, David Greene has an eye for detail which makes the film always attractive to look at ... and he gets a solidly intelligent performance from Bogarde and spirited support from Susannah York.

"[5] In his 12 March 1968 review, Chicago Sun Times critic Roger Ebert said [Sebastian] "is a movie that moves confidently in three directions, arriving nowhere with a splendid show of style.

"[7] Variety identified essentially the same problem, complaining that even though the central code-breaking material had "potent angles for a strong film, but, herein, story touches so many bases that it never really finds a definite concept.