As you may have surmised, Capitol and EMI were going nuts releasing theme albums and a handful of singles left and right during the 1970s just because - well, just because they could with no consequence. Thinking as a business (not that there's anything wrong with that) and not thinking artistically, it was decided to release a single featuring the first two songs from the "Sgt. Pepper's Lonely Hearts Club Band" on the A-side and the last track "A Day In The Life" on the B-side.
The dim light bulb went off when it was discovered that a movie was being made using songs from the LPs "Pepper" and "Abbey Road" featuring the (at the time) heart throb Peter Frampton and the Bee Gees. Capitol and EMI saw the opportunity to make $$$.
The single was released in North America on August 14 1978 with the catalogue number Capitol 4612. There was also a promotional white label disc with the designation P-4612 that has the A-side "Sg.t Pepper's Lonely Hearts Club Band/With a Little Help From My Friends" in stereo and folded down mono.
In the UK, the single was also released on September 30 1978 with the catalogue number Parlophone R-6022. Both singles featured picture sleeves. The UK version was added to the EMI singles box when it was officially released.
The single did horribly in the charts for both North America and the UK. In the United States, the single peaked at 71 in the "Billboard" charts. In the UK, the single didn't even enter the top 30 and became the first Beatles' single not to enter the charts. The fact that the single was released in 1978 and the movie did not premiere in the UK until 1979 certainly didn't help.