Actress Sarah Parish talks about her guest spot as a troll in Merlin – and raising money for the hospital where her daughter received treatment

How was it filming in a fat suit covered in prosthetics in the summer?
“After three or four hours of filming I thought, ‘I can’t actually get any hotter or sweatier or more uncomfortable’ and then I just got into the groove. It was actually a really good, fun day, but cor blimey it was hot and hard work!”

Are you a good troll?
“No, she is a really rather nasty troll. She’s very power hungry and crazed with greed and wants to rule Camelot. She takes it upon herself to make a magic potion which turns her into the beautiful Lady Catrina. When Uther claps eyes on her – he hasn’t seen her in years – he instantly falls in love. Along with her charm and grace she sprinkles him with a bit of magic so he’s completely besotted. Even when her magic starts to falter and everyone else in Camelot can see she’s turning back into a troll, he can’t see it. There are lots of funny scenes, it was really great to play.”

So it was good to play a nasty?
“I loved it – hiding behind prosthetics is great. I think all actors do really, the bigger the mask the more fun you can have because the further away from yourself you are, so you can really go for it. The troll was a really funny and well written character and I was playing opposite Anthony Head who is brilliant at comedy so we had lots of laughs.”

We understand you are trying to raise money to fund a counsellor at the paediatric unit where your own daughter, Ella-Jayne was treated… (Ella-Jayne died aged eight months from a congenital heart condition)
“We did a sponsored walk in Vietnam and we’re always doing bits and pieces for Friends of Paediatric Intensive Care Unit. The aim is to raise £100,000 to install a psychologist on that ward to help the children and parents. If you have a child in PICU it can be a very traumatic time and there’s really nobody to talk to. The NHS are so brilliant but the staff are very, very busy, and more often than not you’re left to your own devices. You really need somebody to tell you exactly what’s going on and what’s going to happen and what all the horrible beeping machines mean! Q The £100,000 would employ somebody for three years and then hopefully the NHS would find it in their hearts to say, ‘Actually, this is a good idea, we’ll do this and fund it properly’.”

And Amanda Holden has been helping you?
“Amanda was going to run the New York marathon but filming has got in the way, so she’s hoping to do London. Will I be joining her? I can’t even run for the bus! I am absolutely hopeless, but I was thinking I might try something with swimming, cycling and running. I’m in my 40s now so I don’t think I could do a full marathon but maybe a mini-triathlon!”

Is there going to be a new series of Mistresses next year?
“We’re doing four one-off specials instead of a series. I’m really looking forward to seeing the girls again and I know the storylines are brilliant – although I’m not going to tell you what they are! Hopefully, we have got a very special guest coming in that everyone will be very excited about. We have such a lovely time. It’s not like going to work really, more like having a nice little break with your mates!”

Sarah first appears in Merlin on October 24 at 6.05pm on BBC1.

If you would like to donate to Sarah’s campaign, visit www.justgiving.com/ella-jaynemurray