The song was written before 1982. From Wikipedia - Bill Martin;

As successful songwriters, record producers and music publishers Martin and Coulter became a wealthy and powerful partnership in the music industry.

Apart from being writers/producers of their own songs, they started a publishing company called Martin-Coulter Music, and signed such other songwriters such as Van Morrison, Billy Connolly, Christy Moore, Donal Lunny, Eric Bogle, Sky, Midge Ure and B. A. Robertson.[4]

Although he continued to write music, Martin found himself gravitating to the business side of the music industry by the 1980s. His partnership with Coulter ended in 1983 when Martin bought out Coulter's share of the business. He later sold the company to EMI.[2]