As soon as I saw the title I just knew what the prayer would be and started singing it in my head! Like you I also loved Radio Luxembourg, secretly listening to it on a crystal-set under my pillow (circa 1946?) - 208mtrs, Medium Wave - wonderful
I I still remember the words!
At the end of the day just kneel and say
Thank you Lord for my work and play,
I've tried to be good, for I know that I should,
That's my prayer for the end of the day.