The actress, who portrays Alison Laithwaite in the 1960s-set BBC drama, opened up about the tougher moments during an appearance on The One Show today.
Speaking to hosts Matt Baker and Alex Jones, the 35-year-old admitted she had to do several takes of a scene in which her alter ego catches a scorpion.
Despite having a “wrangler” on set, Jessica commented: “Yes [I was in the room]. That was me! Numerous takes had to be done because… I was sure I could do it.
“The director wanted me to be really cool as Alison. But as soon as I did it, I was like, ‘Argh!’ It was horrendous.”
The Last Post: Jessica Raine has opened up about playing Alison
The Last Post: Jessica Raine has to reshoot a scene involving a scorpion
Jessica went on to discuss the best thing about her naughty role and it might not be what many would have expected.
She continued: “She’s my favourite character I’ve played so far, ever. It was a real transformation.
“I’d stand in the make-up truck every morning - in the starfish position - with at least two make-up artists with tanning mitts going, ‘Go!’”
The Last Post:s Jessica Raine said she loved being tanned for the role
The Last Post: Jessica Raine said it is her favourite role to date
Jessica also added: “It was not just that, but I did enjoy being very tanned. She’s kind of self-destructive, witty and she’s climbing the walls with frustration and boredom, but she just wants to have fun.”
The Last Post follows the British army unit flighting the Yemeni insurgency in the Middle East, as well as their wives and children who live there.
The One Show airs weekdays at 7pm on BBC One, while The Last Post continues Sunday at 9pm on the same channel.