I think you might be right about it being Jock Purdon, his Wikipedia page mentions a song called "the Cotia Banner", and I beleive this song involved a banner being carried. I Can't find the lyrics to "the Cotia Banner" though, apart from the first verse:

Unfurl the 'Cotia banner boys
Where are the rebels bold
That marched behind the banner
On Gala days of old
It was once said
That they were red
Black listed I've been told

Does anyone have the full words to it?