Hayley Atwell felt very "insecure" during her 20s

Speaking to The I Paper, Hayley said: "I know what my taste is in people now. In my 20s, if I was at an event or dinner party and felt insecure, I'd worry I wasn't enough. Now, I realise it's generally because that person's a bit of a d**k, so I'll talk to someone else or just leave. Life's too short."

Hayley has also learnt not to be so "sentimental" about friendships she makes on acting jobs.

The English actress used to feel very rejected when people she thought she had formed close bonds with on set would cease contact after wrapping the project, but now she accepts it's just the nature of the business.

She said: "I'd form intense bonds with people on jobs and think I'd be best friends with them forever, then be heartbroken when it finished. I'm not as sentimental now, and I trust myself enough to know I'm good at what I do, so if someone says no to me I look elsewhere rather than worry about persuading them otherwise."

The 'Agent Carter' star will be seen as Caroline Mortimer, who is a cruel British mistress who lives on her brother's sugar plantation in 19th century Jamaica, in new BBC One drama 'The Long Song', and she admits that portraying "unlikable" characters is an "exciting" prospect for an actor.

Hayley said: "Heroines have got to have the audience wanting them to succeed, so you can't be unlikable, especially in America. Here, my favourite actresses are so likeable in how unlikable they are.

"Now I'm playing more multi-faceted and ambiguous characters. They're further from who I am and that's where the exciting stuff is, slightly on the edge."

'The Long Song' is on BBC One at 9pm from Tuesday (18.12.18) to Thursday (20.12.18).