It's really commendable for the creators of "Des" to chronicle the story of Dennis Nilsen's conviction without ever venturing in to territory which could've so easily become sensationalist or disrespectful to any of his victims - had other people been entrusted to helm the major undertaking for ITV instead.
Hence, for them to have concluded the series with this final episode - making it until the very end - whilst additionally ensuring not a single scene ever did a disservice to those who suffered as a consequence of his actions - avoiding making the same obvious mistakes so many other real life crime dramas have often made in the past - is truly remarkable & worthy of the audience's genuine appreciation.
It's uncomfortable to sit through but undoubtedly recommended, regardless.