Unforgotten Guest cast, played by Janet Dibley Episode 3x03: Episode 3 (Jul 29, 2018) Episode 4x01: Episode 1 (Feb 22, 2021) Episode 4x02: Episode 2 (Mar 1, 2021) Episode 4x05: Episode 5 (Mar 22, 2021) Episode 4x06: Episode 6 (Mar 29, 2021)