score:2
Nope not at all. Anybody who goes for a tour to the U.K. is inevitably going to pay different accounts in the U.K. one way or another. Even hotel booking is one example.
Paying for a conference you are applying a visa for is certainly not a red flag at all.
Just note that they advise against making paid travel arrangements before securing your visa in case they refuse it. But if paying for the conference is a prerequisite for registration, it is not suspicious at all.