The actual house is in NI and they've CGI-ed the background. Because the city is fictional they can mess with the geography. Where the Corbetts live is ambiguous and just meant to be far away enough that Steve has to have an excuse to drop in (he says he's on a job in the area).I thought it was all filmed in and around Belfast? I didn’t think there was anywhere so high up in Liverpool
Do the entire team know that Farida was Officer J? I found it odd that Chloe said Officer J on the phone to Steve when they found the phones. Maybe I'm overthinking and it was just so the audience would tie it together?