Alana_Morgana asks: Are you going to introduce any new characters from the legends in Series 5?
"We are introducing more, yes. We’re doing some more legends, to be fair. I think that’s a better way of putting it. There’s plenty of legends appearing, although we always want to put a different spin on it.
"It’s interesting, I think you guys did
a ‘stories we’d like to see’ piece – well, at least two of those you will see, although perhaps not quite as you expect!"
You’ve got Liam Cunningham (Game of Thrones) guest starring this year, along with Lindsay Duncan and Janet Montgomery returning too. Do you have a list of dream guest stars for the show?
"We do! We also increasingly hear about people who want to be in it and sometimes that gloriously matches the part. It’s all about lucky really. We’re genuinely surprised and delighted when we hear who wants to do it.
"The problem we have is that as our character base gets stronger and larger and richer, we actually have less guest stars. We now don’t have anything like as many meaty guest roles as we did in the first two series.
"
We’ve got a big cast now. We’ve got a whole bunch of Knights who very developed characters in their own right and want to develop them further. There’s plenty of regular characters that we feel we want to write about.
"But we have some fantastic people in this year.
We’re happy to officially say that Alexander Vlahos is playing the older Mordred."
Will Mordred be around for a while in Series 5? "Yes, he’s in a lot of it." 
When you first started the show and had a rough five-year plan, did you have a wish list of characters from the legends that you wanted to cover?
"When we first started the show, we were more conscious of what we couldn’t do than what we could, in fact. Because at its heart the legend is very dark, when we began
Merlin – and we were in an earlier transmission slot back then, going out at about 6.15pm – we felt we had to be very careful about which ones we did and had to change quite a lot.
"Now that we have King Arthur and the Knights of the Round Table, it’s actually far easier to plunder those legends."
The show’s been getting slightly darker each year, will that pattern continue with Series 5?
"
Probably yes, I think that’s fair to say. We don’t anticipate transmitting any earlier in the evening than we did last year, so we’ve got to deliver a show that works for an audience in that slot."
http://www.cultbox.co.uk/interviews/...es-5-interview