The version I learned from Anne Jackson and Jennifer Armstrong went as follows:

What's the use of wearing braces
hats and spats and boots with laces
these affairs you buy in places down on Brompton Road.
What's the use of wearing cotton
studs that always get forgotten
These affairs are simply rotten
better far is woad.

Woad's the stuff to show men
Woad to scare your foemen
boil it to a brilliant blue, and rub it on your back or your abdomen
ancient briton never hit on anything quite like woad to fit on.
neck or back or wher you sit on, woad for us today.

Now, I've forgotten the second verse, darn!

But it was followed by:
Romans save your armor.
Saxons your pajamas!
Hairy coats were made for goats, gorillas, yaks, retriever dogs and llamas.
March on Snowdon with your woad on, never mind that you get rained or snowed on.
Never need a button sewed on.
W O A D woad.