What comedy filmed in black and white in the 1960's in less than 7 weeks, featuring a "clean old man", was rated by time magazine as one of the all time great 100 films?

The comedy film was " Hard's day night".

Explanation:

This was the first film by The Beatles. It was written by Alun Owen and directed by Richard Lester. Released in 1964, top of the Beatlemania era.

The film reflects a day and a half on the life of the band, with surreal components and cinematography innovations for the time. The film became a Cult classic and was part of the 2005 list of "100 Timeless and Essential Movies" from Time Magazine.

It was pretty surreal; a mix of interviews, rehearsals, performances, the band running away from fans, scenes taking place on a train, a room a car... ( which is said that is how the band felt while on tour) Paul taking care of his grandfather, the "clean old man",  who was interpreted by Wilfrid Brambell. He was famous in British TV for his role in "Steptoe and Son" where he played a "dirty old man" so this was an allusion to that show.

This was the first of the four movies from the Beatles that came afterwards like; "Help!", "Magical Mystery Tour" and "Yellow Submarine".

The soundtrack became a cult as well, featuring songs like; "A Hard Day's Night", "Can't buy me love", " And I Love Her" and " Things We Say Today" which became classics.

Some of the footage seen in the film are takes from real life, like the starting scene where the band runs from their fans. Also some of the scenes were based on real life experiences from the band such as a passenger on a train asking them to turn down the radio, or convincing a fan that recognised one of the member of the band that he was not really him. It is said that a lot of improvisation was left on the film as well.