William "Junior" Campbell (born in Glasgow, Scotland on 31 May 1947) is a Scottish composer, singer-songwriter and musician. He was the co-composer for Thomas the Tank Engine & Friends with Mike O'Donnell, from its debut in 1984 until 2003, and TUGS. He was also a founder member, lead guitarist, piano player and singer the Scottish band "Marmalade", formerly "Dean Ford and the Gaylords", from 1961 to 1971.