Complex sentence: He was also an engineer on several of the albums by The Beatles up until 1965 when EMI promoted him from engineer to producer-the last Beatles album he would be involved with to a substantial degree would be "Rubber Soul".
Split into simpler sentences: He was also an engineer on several of the albums by The Beatles up until 1965 when EMI promoted him from engineer to producer. The last Beatles album he would be involved with to a substantial degree would be "Rubber Soul".