Stephens seems to have been a part of a benefit band called Solent Breezes, which dedicated its income to the Jubilee Sailing Trust. They put out a cassette (SEAWHEELS) which has images of its liner notes online. From this cassette, it appears the song you're after is entitled "4 O'CLOCK ON THURSDAYS".

This cassette seems to me to be the most complete list of Stephens' songs and their themes, so I'll reproduce it below. The only problem is that the most complete images of the liner notes of I've been able to find are from the Polish edition of the release and are, unsurprisingly, in Polish. I used Google Translate to convert them to English, and made minor corrections to obvious typos/translation errors, but I speak no Polish, so I won't pretend it's authoritative. This was supplemented with the English song descriptions I was able to find in brackets -- [[ ]] -- after each entry from the translation.

We are pleased to present to lovers of shanties and sea songs a cassette by the English band SOLENT BREEZES. This group has been associated with the musical traditions of the Solent region from the very beginning, and with the activities of the Jubilee Sailing Trust. The income from numerous SOLENT BREEZES concerts is entirely allocated to the implementation of the goals of this institution. The leader of the group is a talented musician, instrumentalist and vocalist -- already known among Polish sailors -- Ken Stephens.

The SEAWHEELS cassette was recorded in Great Britain, at Cave Studios, Portchester, Hants

Produced by Nicky Wilde, music and lyrics by Ken Stephens, arrangement by Chris Robson.

SIDE A
1. SEAWHEELS About people in wheelchairs who sail the sea. The standard song of the Jubilee Sailing Trust. [[Wheelchair Sailors don't get their sea legs]]
2. HERZOGIN CECILLE About one of the great sailing ships that sank near South Devon. [[One of the great sailing ships, wrecked off South Devon]]
3. MAGNIFICENT MUSKOGA The story of one of the first tankers under sail. [[An early sailing Tanker]]
4. DIAMONDS DANCING About the treasures that the wind gave birth to. [[Windborne treasure]]
5. GREASE THE WAYS A melody sung during the launching of ships in old shipyards. Still waiting for the words... [[An old launching tune, begging for words]]
6. TIDES AWAY About the hard work of the port people. [[QM's have much to do in harbour]]

SIDE B
1. SURVIVOR LEAVE A sailor who survives the sinking of his ship is entitled to a special leave. [[Can apply to any naval conflict]]
2. 4'OCLOCK ON THURSDAYS The advertising slogan of the Union Castle shipping line. [[Union Castle lived by the beat of the engines and the clock]]
3. WRECK OF THE CLARENDON About one of the many disasters off the Isle of White. [[One of many I.O.W. shipwrecks]]
4. BIRKENHEAD DRILL The story of the birth of the shore rescue service. [[The origins of lifeboat drill]]
5. FLUKE ALLEY About an old street in Liverpool. [[An old street in Liverpool]]
6. ATLANTIC CONVEYOR About a ship that never came back. [[A ship that never came back]]

* The English version of the cassette does have an active listing on eBay (click) for only 3 pounds -- someone that side of the water should snatch that up. I'm tempted to, but the shipping is more than quintuple the cost. Still may, though...