According to the Internet source given below, Gavin together with his brother Ian formed The Sutherland Brothers and were a Scottish folk and soft rock duo. From 1973 to 1978, they performed with rock band Quiver, and recorded several albums and toured as Sutherland Brothers & Quiver.
Gavin Sutherland was born in Peterhead, Aberdeenshire. He is listed in these webpages as the composer of Sailing
which was made famous by Rod Stewart who covered it.
||The Sutherland Brothers
||Biography by wikipedia.org.