George Cole plays a meek, rather put-upon bank clerk, who one night at the music hall is hypnotised, and a whole new side to his personality comes out. he begins to behave in very peculiar ways, both at the bank and at home. Particularly hilarious are the scenes where he gets romantic with Joan Sims, playing a parlourmaid who yearns for romance and excitement.
The rest of the cast includes some good performances too, especially James Hayter as an eccentric doctor, and William Hartnell, dead-pan as usual, as a detective. Jon Pertwee plays George Cole's slightly shady brother, who starts the trouble in the first place.
I thought this film was very funny from beginning to end, and I am a little surprised it is not better known, I must admit I had never heard of it until I discovered it on amazon.