Aren't they copyright to Oliver Postgate?

The one I'm having trouble with starts off

Rain rain go away
Come again another day
...
...
...
(then 3 more lines with the same rythm and rhyme, and ends with)
Hopscotch in the garden.

2 more verses of variations on the theme.

I feel that I should know the tune for 'Rain,rain' but all I can sing is the tune for '1,2,3,4,5 once I caught a fish alive'. And I dont think any version I might remember had that short last line.