The 32-year-old actress was recently cast as the lead role in 'So Much Love' - an upcoming biopic following the life of the iconic singer - and admitted that turning up after a night of drinking and smoking can help her channel the performer's signature husky voice.
Speaking to the Daily Express newspaper, she said: ''I'm playing Dusty Springfield next year in the film 'So Much Love'. If I wake up the next morning and I've smoked the night before and I am a bit hungover then I sound more like Dusty.''
Although Gemma is over the moon to be playing the 'Son of a Preacher Man' hitmaker, the 'Quantum of Solace' star admitted that she didn't quite get the reaction she wanted when telling her mum about the new role.
Gemma revealed: ''She said 'You can't play Dusty, you haven't got blonde hair!' and I was like 'it's aright it can be fixed mum.' ''
The movie will be penned and directed by Phyllis Nagy, who was nominated for an Oscar in 2016 for her screenplay for 'Carol', whilst Number 9 Films will produce.
Filming is set to take place in the UK and US in early 2019, and Gemma has revealed that she's always been inspired by the 'I Only Want to Be With You' singer, and is delighted to be portraying her.
She said: ''I have been an admirer of Dusty Springfield since I was a teenager: her effortless husky voice, the way she conveyed emotion through music, how she helped bring Motown to the UK.
''Dusty was ahead of her time in many ways and inspired so many future artists. She was generous, witty, mercurial, shy, extroverted and a true English eccentric. I simply cannot wait to play her.''