The star of the stylish gangster drama reveals five secrets from the set

1 I play Aunt Polly, part of the Shelby family at the heart of the show. She has several vices including a fondness for cigarillos. I had to get through quite a few during the series – I dread to think what my lungs look like! But the actual process of smoking comes easy – I had years of practice!

2 Polly’s clothes were hand-picked by our brilliant costume designer Alison McCosh. She sourced them from auctions, sales and markets across Europe and it’s so refreshing to be wearing clothes that have never been seen on TV before. You sometimes get presented with dresses and think, ‘Didn’t I wear that in an Ibsen or a Chekhov – or an episode of Inside No 9?’ Not on Peaky Blinders!

3 The Shelby clan sometimes do the Peaky Blinders walk, where we glide forward together in a line, in slow motion, accompanied by background music. The whole thing is choreographed but can still be tricky. The first time we did it in this new series, a couple of the actors needed to have the music playing to stay in step.

4 Style is essential to the show and we think hard about every scene. I suggested a long tracking shot for a scene where Polly is being entertained by a young acquaintance while dressed in black lingerie, before she slowly exhales the smoke from her cigarillo and delivers a single line – ‘My beautiful boy!’ – which sums up exactly how much fun she’s been having!

5 Polly is not overly involved in the more violent scenes, but professional armourer Mark Shelley is on hand to make sure the actors feel comfortable. He answers their questions about knives, axes, and corkscrews so they feel confident when they go into a scene holding a weapon.

Helen with co-star Sam Claflin in the show