Line up: John Lennon (vocal, rhythm guitar), Paul McCartney (vocal, bass),
George Harrison (vocal, lead guitar), Pete Best (drums)

Paul, John, Pete & George

After the Beatles' return from Hamburg to Liverpool without Stuart Sutcliffe in late 1960, the band had engaged Chas Newby at the bass in order to be able to perform four shows in December.
In early 1961, with Chas Newby back at the college, the bass position falls vacant once again. George Harrison refuses an invitation from John to take up the instrument. Paul accepts the invitation and switches from his position on rhythm guitar and/or piano.

Paul initially plays a cheap Solid 7 model with three piano strings. He will soon return to Hamburg and purchase an unusual Hofner "violin" bass guitar.

Paul takes up the bass, a Solid 7 model.	Later on, he purchases the famous Hofner bass.

Through the efforts of Mona Best, The Beatles gain playing access to the Cavern Club in Liverpool. This will be a determining factor in the growing popularity of the group.
Outside the Cavern....	The band live at the Cavern.

The Quarry Men had already had 2 venues at the Cavern in 1957 and 1958. But the Beatles' first debut at this place occurs on February 9th, 1960. The Cavern will become The Beatles' second home until August '63 and will have a determining role in the history of the group, allowing them to become the biggest entertainment phenomenon in Britain.

In the dressing room of the Cavern.	The Beatles having fun on stage...

The Beatles have their second trip to Hamburg for an engagement of 13 weeks from April 1st to July 1st.

They are playing at the Top Ten Club over 92 nights. There, they play their own performances, and in addition, they sometime back Tony Sheridan on stage (as they already did in late 1960).
Paul and George at the Top Ten Club, in 1961.	The Beatles already performed at the Top Ten  in late 1960.

The collaboration with Sheridan lead The Beatles to accept to back him during a session dedicated to the recording of five numbers performed by Tony (among which is My Bonnie Lies Over The Ocean). This recording session on 22 & 23 June is an opportunity for The Beatles to make two more recordings without Sheridan: Ain't She Sweet (Ager/Yellen) & Cry For A Shadow (Lennon/Harrison). 
The result of these sessions will be a release of two of the recordings in August 1961: My Bonnie and The Saints, credited to Tony Sheridan and the Beat Brothers.

The Beatles with Tony Sheridan in 1962.