The inspector is presented as unusual by his personality, conduct and expressed views. Throughout the act, Priestley makes the Inspector say and do things that an audience would not expect of a conventional policeman.
A conventional policeman would be polite and professional. We would expect an Inspector to be discrete in his work as to avoid causing problems or drawing undue attention at the case and wrongdoings of the Birlings. He should be sensitive so he doesn’t offend anyone. A normal inspector would take suspects to the station and follow more conventional policing methods.
The Inspector is not like the one described above. His personality is judgemental and he expresses opinions on the acts of others. When Sheila bursts out about the girls being people and not just “cheap labour”, the Inspector shows his agreement as he says “I’ve had that notion from time to time”. Here he passes judgement on the way Birling treats his workers by suggesting that they are described as objects so often that he only remembers that they are people some of the time. In this way, the Inspector criticizes Mr Birling’s firing of Eva and makes his feel guilty. This is not the role of an inspector. He should be finding things out by asking questions and taking answers relevant to the case, not speaking his mind on social matters and making suspects regret their actions by telling them they’ve done wrong.
The Inspector’s aggression makes him unusual. Rather than conducting the investigation in a respectful way, he takes the household by surprise and intimidates them with a vivid description of Eva’s death – “burnt her inside out”. He shocks them with this description to get their attention and make the suspect understand the severity of events. This is successful as he makes Eric exclaim involuntarily, showing how the Inspector wields the power of knowledge which he can use over them. Knowing things that