I know that Colin Dryden sang this song (thanks to the
recording his niece, Naomi published), but does anyone know if he wrote it?

Searches for the title or snippets of the lyrics haven't turned anything up. Naomi has listed the author as 'Colan Campbell' (Colin?) but there is another song with the same name by a Colin Campbell, and it's isn't this one. I know another Colin Campbell was involved in the group 'Extradition' with Colin Dryden, so maybe that is the confusion source?

My best guess at the lyrics below:
        
Smoke your cigarette and put your hand upon my shoulder,
Smile at me and part your lips, make pretend you’re older,
Than the years that you really are.

Walk your walk across the porch, brush upon you swearing,
Flip your skits a little more, Watch the boys all staring,
Then you cry, as you really are.

Little girl in big girl’s clothes, Eyes that sparkle brightly,
Face that shows you sit for hours, before your mirror nightly,
But you’re fine, as you really are.

You don’t need the likes of me, I’m not even lonely,
Satisfy your vanity, with someone who can’t know dear,
Just how young, that you really are.

And a recording I did to celebrate finally presenting my research on Colin to the National Folklore Conference yesterday here.