The guillotine/off with their heads protest was intended as a metaphor for ending the rule of monarchs.

In a democracy, a political protest using just this sort of street theatre would be constitutionally protected.

But Britain is neither a democracy, nor does it have a bill of rights to protect it's citizens.

And McGrath--is yer head always stuck in the "oppositional thinking" sand like that? There are always more than two sides to a story...