The series - The Bletchley Circle - is not quite as daft as I've made it sound and it's an intriguing premise. Bound by the Official Secrets Act to stay silent about what they did 'during the war', even keeping the secret from husbands and family, a group of women found themselves, often unwillingly, solving a series of murders for the original short series.
This time around we have four new episodes, split between two stories, set one year on in 1953. Hattie Morahan joins the core cast of Anna Maxwell Martin, Rachael Stirling, Sophie Rundle and Julie Graham.
And what has compelled the team to reunite in their crime solving spare time? A former Bletchley Park colleague is accused of murder and set to hang for her crime. But did she shoot a distinguished scientist through the heart, despite being found holding a smoking gun over his body?
According to ITV The Bletchley Circle received a high audience share of 23 per cent in 2012 - running second to Endeavour amongst new drama titles. Ratings hit an average of 5.6m and it was reviewed well in the US too, we're told - PBS broadcast it in the Sunday night slot alongside Call The Midwife and Mr Selfridge. Looks like British TV really is aiming to wrap up the whole costume drama sector.