The man who played the Iron Lady

Nallon was offered his puppet but asked for Alan Bennett instead

Meryl Streep has already been honoured by the New York Film Critics Circle for her role as Margaret Thatcher in The Iron Lady and been nominated for best actress at the Screen Actors Guild awards and the Golden Globes. More nominations are sure to follow.

However, UK comedian and impressionist Steve Nallon is still responsible for one of the most famous portrayals of the former Prime Minister, first in live club shows and then with the comedy series Spitting Image.

When did you realise you could impersonate Margaret Thatcher?

Around 1975, she had just become leader of the Conservative party and Mike Yarwood, who was the impressionist at the time on telly, he tried her and it wasn't that great. I thought I'd have a go and she has that odd quality of sounding half-male and half-female which I think all adolescent boys have when their voice is breaking. That's when I realised I could do her.

When did it start to take off?

When I started playing the northern clubs because they really hated her and I got a lot of mileage out of that. Even before she became prime minister, they didn't like her very much because she was a posh Tory. In places like Yorkshire, she went down the way you would expect it to go down.

What are the challenges when you are portraying someone in government?

I used to do a question and answer with the audience, I had no act, I just dressed as Thatcher and went out to take questions. So, the difficulty once I'd got the voice was to know everything about her, I had to read all the books and newspapers and keep up to date, I had to know all the cabinet ministers, what was going on in Europe. If I went on Mastermind, Margaret Thatcher would be my specialist subject.

Do you still get many requests for her when you play live shows?

People would much rather hear me do the characters from Family Guy and, to be honest, they don't know her so you could be doing the best impression and it wouldn't make any difference. They are aware of her but they are only aware of her in the same way that you might be aware of someone like Harold Wilson or Jim Callaghan. It's the same for young people today, if I spot some grey hairs in the audience then, yes, I'll do Thatcher.

Recent portrayals of Thatcher have been quite sympathetic, have people stopped making fun of her because she is elderly and infirm?

Yes I think that's true, there's less polarisation I think with Thatcher, you either loved her or hated her. She was either a figure of fun or an iconic hero but the truth is always more complicated and I think as the years go by, people will see more of her human side, her marriage and the fact that she was clearly devastated when it all came to an end. Looking back now, perhaps her legacy is Tony Blair rather than Cameron. The fact that nobody dismantled politically what she achieved.

Do you expect a resurgence in interest because of the new film The Iron Lady?

Yes, but it will be a 24-hour thing. I'm positive it will happen but it won't last long.

Steven Nallon was speaking to BBC Arts and Entertainment reporter Kev Geoghegan.

The Iron Lady is released across the UK on 6 January.