 Caroline Quentin (qv) was heavily pregnant with her first child  during the filming of the third series and her bump is hidden  throughout by baggy clothes and careful framing. After a hot day of  filming scenes in Derbyshire for this episode (where her character  is taken hostage and dragged around a field with a gun in her  mouth), she returned home to her Central London flat where she  immediately went into labour 10 weeks early. She gave birth to Emily  by Caesarean shortly afterwards.