Sadly I have the feeling it is pretty hard to find in English. Original title is La giornata d'uno scrutatore.
Not sure if it's still in print, but it has certainly been published in English.
Yes I know. I don't know if it is still in print, I think it might be in some volume together with his other short novel from the same period La speculazione edilizia.
A quick search has it easily available in English on Amazon, so presumably it can be found from less-evil online retailers too.
Glorious news!
I actually tend to think all online retailers are intrinsically evil, although yes, Amazon is likely the evilest.