It maybe set off the vote ring detector because your costumers seem to be located all around London. So it may be possible that some of them shared the submission with other London users or that because they know your company they up-vote it; making it look like it was ringed but it was just selection bias.

Anyway this is a tricky problem; because at the end of the day intent is a fundamental part of vote rings and that can be really hard to see by algorithms alone.