The trumpet part was added after the rest of the song was finished. McCartney was watching the BBC when he saw a group called The New Philharmonia perform Bach's "Brandenburg Concerto #2." He got the idea to add a trumpet part, and asked the group's trumpet player, Dave Mason, to play on this track. Mason brought nine trumpets to the session, eventually deciding to use a B-flat piccolo trumpet. Mason, who is not the same Dave Mason from the group Traffic, played on a few other Beatles songs, including "A Day In The Life
," "Magical Mystery Tour," and "All You Need Is Love
McCartney credits Beatles producer George Martin for translating the trumpet line to Mason, as Martin spoke musician. McCartney sang the part he wanted, and Martin transcribed it to a piece of paper that he gave to Mason. It's one of many examples of how Martin helped the group execute their boundary-breaking ideas.