We do.
Plenty of us were there, too.
Cheers to everyone who marched yesterday, using our democratic right to peaceful protest. And with a turnout of an estimated 1.8m, don't forget that each of us were also representing those who couldn't make it due to work, rehearsals, family and other commitments, but were there in spirit and asked us to remember them there. I had at least 10 requests to "march for me".
Who knows if it will make any difference - but that is no reason not to try.
Similarly, if you haven't yet signed the Revoke Article 50 petition - which at time of writing is just short of 5m - please do so here.