Rupert wrote an article for the BBC’s TV Blog website during the lead-up to the fourth season finale of Merlin. He talks about how he was cast for Sir Leon, and how the character has grown since then. Among other things, Rupert said:
Sir Leon started off as a very small role. I was only meant to be in one scene jousting Arthur, but at the read-through I was given a couple more lines. I arrived on the first day of filming series two, having learned my line for that day – “The King commands your presence immediately” – and when it came to my first take I fluffed it.