The real police inspector at the end of J.B Priestly’s ‘An Inspector Calls’ defeats the point of the play.
At the end of the play, the family is left ‘dumbfounded’ as they are informed a (real) police inspector is on their way to investigate a suicide, but wouldn’t it make more sense if the audience is left with the realisation that only a fake police inspector (or a fake human being, for that matter) would actually go out of their way to bring light to such an event? This message would convey Priestly’s ideas of the current state of society in all its unjust glory rather clearly, should the audience take a minute to consider it.
I would also deduce that, regardless of what is convenient for the plot, such an inspector would not be dispatched for a suicide investigation anyway, especially not given the vague way Goole states he knows so much about Eva for (her diary). The fact an inspector comes directly to the Birlings’ place is downright unrealistic.
Overall, I believe that the revelation that Goole wasn’t a real inspector does the trick just fine, shedding light on both the lessons learnt by the younger generation (Eva and Eric, who feel guilt regardless of Goole’s legitimacy) and the lack thereof by the senior Birlings and, I suppose, Gerald, too.
The closure the audience gets after hearing of the arrival of a real inspector feels undeserved, and seems to dumb down the message of the overall play, as the Birlings seem to soon be held truly accountable for their actions, something which would not happen if society on the whole was truly how Priestly sets in the rest of the play (which I believe it is.)