This could have been six episodes given the depths of the real story, but it was brilliant to keep it to four and make it economical by focusing on the sick psychology of the perpetrator. For example, the show doesn't get into his real-life side job as a paid prostitute, but the scenes of him taking shirtless selfies hints that he's the type who would be on the game. We don't get the deeper history of his relationship with his toady Martyn but in a brief scene of public humiliation we get the psychology of it.
The script gives the audience enough credit by not "revealing" Ben's evil fakery as a suprise. The romantic situation he engineers with lonely old Peter is so suspect that we know he's bad before we ever see him behave other than perfectly kind and gentle. When he does start behaving like an egotistical jerk it's not meant to be jarring, and it isn't, but it's deeply creepy because we don't know how far it will go.
The script gives the audience enough credit by not "revealing" Ben's evil fakery as a suprise. The romantic situation he engineers with lonely old Peter is so suspect that we know he's bad before we ever see him behave other than perfectly kind and gentle. When he does start behaving like an egotistical jerk it's not meant to be jarring, and it isn't, but it's deeply creepy because we don't know how far it will go.