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From what I can see it's unlikely to have got planning permission (it wouldn't qualify for permitted development as it's within 2m of your property). I would say that the lack of flashing between the roof tiles on the porch and the wall it's leaning onto is a strong indicator that the work has not been signed off by building control.
As others have said it's not worth mentioning though.
At risk of sounding megafussy is it worth mentioning this subtle encroaching by next door neighbour before buying a house?
I know it is probably not worth the stress but I wonder if it is worth to record the cheekiness of such fine porch since everyone has brought lawyers to the party... just in case next door wake up felling like annexing further territory one day