Doctor Who’s Matt Smith and Karen Gillan were almost the stars of Merlin – but the series creators say they have no regrets

But speaking to RadioTimes.com during a live Q&A last night, Julian Murphy and Johnny Capps said they had no regrets about their casting choices - with Colin Morgan and Angel Coulby having eventually starred in the series.

"It was a really hard show to cast, it was very hard to find the actors that you thought had that likability and charm," said Capps.

"Funnily enough Karen Gillan was also on the shortlist to play Gwen. Looking back on the recalls now there were a lot of really brilliant actors that we nearly chose.

"But there wouldn't be anybody that we would, looking back, recast. It was just one of those shows where all the cast just gelled beautifully, and not only did they do the parts brilliantly but they were all a joy to work with."

Meanwhile Murphy reiterated that the main reason they opted for Morgan over Smith for the lead role was purely to do with age - with the younger Morgan a more suitable fit for the role.

"The reason we went for Colin rather than Matt was very straight-forward - Colin was younger," he said.

"He brought more innocence to it and we felt Merlin had to begin this series at least almost as an innocent boy who was going on a journey to manhood.

"So it's incredibly hard to imagine what it would be like now, but a Merlin who was less innocent than Colin in that episode, less open and willing to show that vulnerability that he did would have meant a different show."

Of course, within a couple of years Smith and Gillan would be starring in series five of Doctor Who, with both going on to huge success, while Merlin became a big hit over its five series run - so it's safe to say it worked out well for all concerned in the end.