The actor, who plays AC-12 newcomer DC Chloe Bishop, admitted she “freaked out” after turning up at the audition and seeing a script that revealed the show she would be reading for.
In an interview with The Times (£), Shalom explained: “Things have working titles so you don’t always know what they are and the script said LOD6.
“When I opened it, the first line Chloe had was an AC-12 interview. I was absolutely freaking out. There was so much to learn.”
Shalom revealed she first auditioned for the part of DC Bishop at the start of February 2020, and there was around a week before she got the job, with filming starting shortly afterwards.
Of joining the established cast, she said: “I turned up to the read-through and there were all these mega British actors that I’ve loved and adored for so long.
“Adrian [Dunbar, aka Superintendent Hastings] is hilarious. Vicky [McClure, DI Fleming] is amazing and very funny. Martin [Compston, DI Arnott] was my rock — he would say, ‘Don’t worry, we’ve got the whole day to film this, and if you mess up we’ll go back to the beginning and start again. But you’ll be fine.’
“I honestly could not speak more highly of them all.”
During the interview, Shalom described her character as “a good egg”, appearing to shoot down fan theories Bishop might be corrupt.
Asked if there is more to her, Shalom replied with a laugh: “I don’t know.”
A trailer for Sunday’s series finale has promised viewers that the identity of ‘the fourth man’ – otherwise known as ‘H’ – will be revealed.
The internet is already flooded with theories ahead of the finale, as many fans believe Marcus Thurwell is actually alive, after the character was found dead at his Spanish villa – and some of then claim to have the proof.
Suspicions have also been raised about DCS Carmichael, as some viewers spotted what they believe might be a clue that confirms she’s ‘H’.
Line Of Duty concludes on Sunday at 9pm on BBC One.