Oscar winner Helen Mirren has said she still fears she will be "found out" as she revealed her struggles with imposter syndrome.

The 76-year-old actress is set to receive a Lifetime Achievement Award from the Los Angeles Screen Actors Guild (SAG) next week.

Previous recipients of the accolade include Robert De Niro, Julie Andrews, Elizabeth Taylor and Gene Kelly.

Speaking to You magazine about the award, Mirren said: "Yes, it's extraordinary. I genuinely do not feel I remotely deserve it, except that I’m still alive and working.

"I’ve done some wonderful films and I’ve done some pretty awful films. It took me by surprise, completely. A great honour."

The star won an Oscar, a Bafta and a SAG award for playing Queen Elizabeth II in The Queen, adding to her collection of Emmys, Baftas and a Tony award.

Elizabeth Taylor

Mirren added: "I think of myself as still being the way I was in my mind, in my body, through my 20s, 30s and 40s: struggling, ambitious, frustrated and self-critical.

"I still feel the same person. I wonder if that ever goes? There’s always that endless, niggling feeling, 'Oh god, I’m going be found out any minute now. I got away with it that time, but the next time I’ll be found out.’

"Because you can never be absolutely sure that you’re that good at what you do.

"It’s not like being a doctor or a surgeon or an architect or a gardener where you can look at your work and go, ‘Oh yeah, that’s really good. It’s a much more mutable thing, our job."

The actress next stars in The Duke alongside Jim Broadbent, which tells the real-life story of Newcastle cab driver Kempton Bunton, who was prosecuted in 1965 for stealing Goya’s portrait of the Duke of Wellington from the National Gallery.

It is the last film from Notting Hill director Roger Michell, who died in September at the age of 65.