Here's the version I heard in the 90s

Ever seen a chap like a Roman candle, sort who never let his braces dangle,
Gladiator bold and furious, running 'round Rome in a skirt so curious
I'm in the bodyguard of Julius Caesar; he's got a phizzog like a lemon squeezer (* phizzog==face)
My name's Marcus, diddly-darcus, permanent address is Rome.

CHORUS: I'm glad, glad, very, very glad; I'm glad I'm a gladiator.
Ancient Rome, that's my home, fried fish shop by the Hippodrome.
I'm glad, glad, very, very, glad, from my helmet to my toes,
My old man was a Roman man, and he left me a Roman nose! 2, 3, 4.. 1, 2, 3, 4...

'Round the Coliseum we go marching, wearing dickeys that are needing starching,
Watched by Nero, he's our hero, sitting up there with a bellyful of beer-o
All day long he keeps on fiddling, Thumbs a-twiddling and fingers diddling.
We must please him. If we tease him, he'll throw us in the lion's den.

I fought a duel with a lion called Nifty, mangy bugger with a leer so shifty.
Roarus chorus, he came for us, I shoved my weapon up his anal quarters.
Gave that lion such a rare old beating, found his hemorrhoids were needing treating,
Oh what a win! Oh what a din! Everybody thumbs up! RAH!

Julius Caesar had a motto, only remembered it when he got blotto:
"Nulli secundus orus randi" He was a bugger on a pint of shandy.
On his banner was a Roman lancer, three French letters and a naked dancer.
He can't fool us, got no toolus, lost it in the Ides of March.

Marcus Anthony, the dirty old shitehouse, lost all his medals in a Rome red light house,
Woke in the morning, all very solemn, couldn't find the end of his Trajen column.
Favourite sport of this Roman rogue is, two pink gins and "off with their togas"
Magnus shagnus, any old bagnus, golly what a Roman wreck!

They were a queer lot, the Ancient Britons. Look at 'em twice and they'd have kittens.
You've read in "De Belli Castri" how we were poisoned by a Cornish pasty.
We lost Marcus to a fair young Druid. She injected him with a poisonous fluid.
With his arse full of woad, he croaked like a toad so we buggered off back to Rome!