The UK unfortunately doesn't have freedom of speech, it has freedom of expression.
> The woman, 22, was arrested "in connection with a breach of the peace," a Police Scotland spokesperson told NPR, adding that she was formally charged and released, and her case is now pending at Edinburgh Sheriff Court.
Just to add, you can also be arrested at speakers corner if you upset enough people there and there is "reasonable cause" that they may become violent, despite you speaking peacefully.
This NPR article is false and clearly doesn't understand the laws of the UK.