Having now listened to this song, as very kindly supplied to me by henry29, I can confirm that it really is the same song as done by Errol Dunkley in 1979. Looks like John Holt changed a few words here and there and then decided to claim a sole writing credit for this one. A day when you learn at least one new fact is always a good day.
Although I can't claim to have heard The Ladybirds' O.K. Fred, the Errol Dunkley version was written by John Holt and came out in 1979, some 14 years after The Ladybirds, and their composer credits read Albimoor & Gary. I would have thought it was a completely different record, especially since John Holt's recording was issued in 1971.
Since you have the record, Henry29, can you confirm that it is the same record as Errol Dunkley?