The show, starring Laura Neilson (played by Joanne Froggatt) and Andrew Earlham (Ioan Gruffudd), is set in a seaside town with visuals including Deal on the Kent coast, Margate, Walmer, and Kingsdown.
However, episode three busted the mythical coastal location after the production made an error and filmed a huge SE4 postcode giving away that segments of the show were filmed in London.
During last Monday’s instalment, it was revealed that Andrew’s son Luke (Jamie Flatters) had made schoolgirl Makeda (Tsion Habte) pregnant.
In a scene where Makeda was waiting for the postman to deliver abortion pills to her at the laundrette, the teenager looked out of the window where a large SE4 postcode could be seen painted on a wall beside Brockley station in South East London – before she made her way to school at by the coast moments later.
The distraction was spotted by eagle-eyed fans who recognised the area and could not help but notice the other Brockley filming locations such as a scene in Noak cafe, Andrew and Luke’s house located just around the corner, and the Waverley Arms pub where Andrew met with Dennis Walters (Peter Davison) for a drink.
Writer Jack Williams told Express.co.uk that executive producer and director James Strong had tried to use a number of seaside locations to bring the fictional town to life.
He said: “He had a specific look in mind and a specific vision of a place he wanted it to be.
“It has to feel specific, but not so specific that it doesn’t feel like it could happen in the world today.
“It has to feel like a very present thing that can happen anywhere and to anyone.”
He added: “Having directed Broadchurch he said, ‘I want to do something very different.’ And then we went to a seaside town.”
Liar episode five airs next Monday on ITV at 9pm.