A PPL holder can fly on his own business. If he is an employee then he also can do so provided he is not contractually required to do so.
I am not aware of an ANO clause which specifically prohibits aerial photography or aerial survey work, so a PPL should be able to fly around and do that and make money out of it.
There is a provision somewhere that the flight must be no more than incidental to the company's business, however, and (if true) this could be the catch.
A dedicated aerial survey business would then require a CPL but more to the point would require an AOC which rockets the cost by 5 digits annually.
I know for a fact of one outfit (a flying school actually) which was contracted to a local radio station for traffic spotting and they had an AOC for that. What I don't know is whether they actually needed the AOC or whether that was some scam by an insider - the school collapsed later following some massive fraud.