The title The Grey Funnel Line is an euphemism for the Navy, equating the colour of its funnels with those of company emblems found on commercial shipping lines. The song, though romantic, does show the boredom, loneliness, and longing for home that afflicts many who work on modern screw-driven vessels, be it naval or merchant marine.
Cyril wrote that song in 1959 and it has been published first on his Argo LP In Port from 1972.