"I know you’re meant to work to target audiences, but I’ve never done what you’re supposed to do. I don’t think I’m capable of it…"

That’s director Paul Schoolman explaining the ambitious, unique and really quite striking StringCaesar. Shot in Cardiff, Canada and South Africa’s prisons, it’s a film showing Julius Caesar’s rise to power, spilling blood and slitting throats – all behind bars.

Starring Derek Jacobi alongside hundreds of inmates, StringCaesar had its UK premiere at the Raindance Film Festival this week. I interviewed Sir Derek after the film. It went something like this:

Thank you.

[Derek smiles]

That happened while he held open the door for me in the toilet.

My brief encounter with Sir Derek over, I then spoke to Schoolman about the production. He explained how many years he’d been working on the film – since 1984. Or, as he accurately put it, “before you were born”. Stopping every few minutes to talk to a friend, colleague or granddaughter, he cuts an enthusiastic figure, satisfied that his project is now complete.