Susan Jameson plays the monarch in an episode that takes a fascinating look at the hidden conflict between the Queen and her first female Prime Minister, Mrs Thatcher.
You became an actor in the early 60s. How did you end up going down that career path?
'I just always wanted to do it. I was one of those awful children who wanted to perform all the time. When I was five, my mother took me to see Swan Lake, the ballet, at Stratford. On the way home, I told her I wanted to be a ballerina, so she arranged for me to have ballet lessons - at some expense, because we weren't well off.
'After a few lessons I think I realised I wasn't ever going to be a dancer. I didn't practise or anything, I was really very naughty. But then I discovered that you didn't have to dance to be on the stage, you could use words instead. So I decided to do that.'
Were your parents disappointed with your career choice? It's a pretty capricious profession, after all?
'Well, I was meant to be at sixth form college doing my A-levels, and I snuck off one day without telling anyone to go and audition at drama school in Birmingham. They took me because I think they took everyone, really. They were just happy to have the money, I think. I got home and told my mother, and I think she just rolled her eyes and sighed.'
Do you still hanker after that career as a ballerina?
[Laughs] 'No. I still like to prance around a bit, but I'm quite happy with the way things turned out.'
Your first acting job was on Coronation Street. Was that a good grounding in the business?
'Yes, it was excellent. It was one of my first jobs, and it really taught me all about working in telly. It was wonderful working with all those fabulous old women on the show. I was in it for seven months, and then I decided I wanted to leave and become a 'serious actress'. So Myra, my character, basically ran off with all of Jerry's money.
'Myra went back on the show some time later, thinking that Jerry might have more money. I had to try and seduce him, but had to wear a pair of winceyette pyjamas, and he had to be fully clothed. I think it would be rather different these days though I was quite glad to have the winceyette pyjamas, actually.'
Did you suddenly start getting recognised for being in Coronation Street?
'Yes, I did a bit. It was quite strange. It still happens every now and again, someone will recognise me from my time in Coronation Street.'
What are the roles in your career that you're most proud of?
'I loved working on When the Boat Comes In. The scripts were so good, there were so many great actors involved, and the production crew and everyone were brilliant. That was a really good experience. Although the lead actor in it was awful.'
James Bolam?
[Laughs] 'Be very careful! That was a great drama to work on and Take Three Girls was very important to me as well - it was the first time that all the leads in a show had been women. Liza Goddard is still a dear friend of mine, and Angela Down, they were great to work with.
'In the end, it's all about the writing, the scripts are what make a project. More recently, I've worked on a wonderful series for CBeebies called Grandpa in My Pocket, which has been a great success, and is really fun to do.'
Which is once again with James. Did the two of you meet while acting?
'Yes, we met filming an episode of The Likely Lads. Although we didn't see each other again for a long time after that.'
So it wasn't a question of love at first sight, then?
'No, not at all. I thought he was loud, and he thought I was stuck up! You could say nothing has changed.'
The two of you star together in New Tricks, but you play Alun Armstrong's wife. Is it odd playing someone else's wife when your real husband is on set with you?
'Oh no, not at all. It doesn't matter in the slightest. You put all of that to one side, it doesn't even occur to me to find it odd.'
What attracted you to the idea of playing the Queen?
'To be honest, I didn't really have time to think about it. I was recording a radio play with Mark Heap about aliens, and then two days later I was down in freezing Dorset playing the Queen. It wasn't until a couple of days later that it really sank in what I was doing and then it became very frightening.'
What do you mean by frightening?
'Playing someone who is still alive, who is so familiar to everyone, and who is so loved by so many people.'
Did you try and capture her voice and mannerisms?
'No, I think if you start trying to do that, you end up concentrating so much on that and not on the script and the role you're playing. You end up trying to do an impression, and you forget about the material. What I did was try and capture the essence of her, I suppose, rather than do an impression of her.'
The film deals with her relationship with Mrs Thatcher. Why do you think we are so fascinated with the relationship between the two, in a way that we weren't with the Queen and other prime ministers?
'I think probably because the two of them are women. I suspect there was a bit of a battle between them, to see who would be left standing at the end. The Queen was born to it, of course, but I suspect that Mrs Thatcher thought she had a point to prove.'
It's fair to say the pair didn't enjoy the closest of relationships, isn't it?
'Yes, I think it is. They didn't agree on everything, and I have a suspicion that The Queen didn't like certain aspects of the way Thatcherism treated the most vulnerable people in society. I don't think they saw eye-to-eye on certain things.'
Like the Commonwealth? Mrs Thatcher's opposition to sanctions against South Africa nearly broke up the Commonwealth, didn't it?
'Yes, that's right and the Commonwealth is very important to the Queen. I think she has great loyalty towards the countries in the Commonwealth, and the countries that used to be part of the Commonwealth.
'She's spent a lot of time out there, and she was there when she was informed of her father's death. So I think she was upset by how Mrs Thatcher's actions affected the Commonwealth, and I think there was probably a constant undercurrent of tension between the two, underneath a cordial surface.'
The scenes of the Queen and Mrs Thatcher together are all veiled comments and icy putdowns. That must have been great fun to film.
'Oh it was, I really enjoyed it. It was wonderful working with Lesley Manville, she was brilliant - and looked disconcertingly like Mrs Thatcher. It was incredibly cold, though, when we were filming. We had to do lots of sucking on ice cubes so our breath didn't come out in huge clouds. I didn't know that was what you did, but it worked very well.'
So it was icy both metaphorically and physically?
'Yes, it was. There was one day in particular that we were filming in the freezing cold, and it was also a day when we were shooting scenes that were very icy between the Queen and Mrs Thatcher.
'We were filming at Longleat, and were just coming to the end of one scene that we were all rather pleased with, when all of the wolves [in the safari park] started howling because it was time for their lunch. It didn't really seem right that the Queen and Mrs Thatcher would have had howling wolves interrupting their discussions, so we had to re-shoot the scene.'
Did making this series change your attitude towards the Queen? Did you warm to her?
'I did, rather, yes. I'm no great royalist, I have to say, although I have absolutely nothing against any of them personally. I just think that some of the money could be better spent going to more needy causes but they are born into their positions, it really can't be easy for them.
'It's certainly not a job I would want - it must be awful not being able to relax apart from on the few occasions when you're alone with your family. So I did start to sympathise with her and warm to her. And I also started to become a little bit more regal as I got into the role.'
In what sense?
'Well, I hope I wasn't bossing anyone around, but as time went on, I found myself thinking, "I would really like a cup of tea, and someone really ought to get one for me."'
Did you refer to yourself in the first person plural?
'Of course. And people close to me would really tease me about it. There was a lot of curtseying to me from my friends.'