Are you expecting me to comb through thousands of cases? Obviously they were arrested for saying legal things, if their arrest doesn't follow a conviction in 90% of cases.
I expect that when you say someone was arrested for speech and it's government overreach (as opposed to a legitimate arrest), you should show us the speech they were arrested for, to back up your claim that it's overreach.
If you're going to claim that people get arrested in the UK for criticising the government, it's reasonable to expect you have an example to hand.