'Gowrie' was a British unrealised deception plan developed by the London Controlling Section to support 'Neptune' (iii) and 'Overlord' by confusing the Germans about the schedule for the launch of the Allied invasion of North-West Europe (1944).

The plan was based on the employment of double agents to 'leak' to the Germans on D-30 that D-Day would in fact be D+45. At D-10 the British minister in Dublin was also to tell the Irish authorities that the German embassy should be closed on the grounds that this was being used as a conduit for the transmission to Berlin of military information vital to the UK: should the Irish refuse to do this, the British minister was then to inform them that this might result in the closure of the border with Northern Ireland, the termination of Irish shipping to and from Northern Ireland, and economic sanctions on Ireland.