On the wikipedia entry Alex Glasgow is credited with writing the song "Dance to your daddy" or "When the boat comes in" - Whichever.

The musical arrangement is credited elsewhere.

There is no doubt that Alex Glasgow sang the arrangement for the television series.

Where I have problem is if in fact Alex Glasgow claimed he wrote the song and claimed it as such to PRS then this at best dishonest.

It would be interesting to find out if such were the case(that Glasgow claimed to have written the song)how much he received in royalties.