If a demonstration, by some dissident group, were to occur at the Royal Wedding, would the crowd react?

Demonstrations have been threatened by Muslim and anarchist groups. The police have indicated that such demonstrations in the vicinity of Westminster Abbey, will not be tolerated. However, that does not mean that they will not be attempted- after all, these groups are not noticeably law-abiding! But if they are attempted, how will the crowd react? My own suspicion is that they might- and so surprise these dissident groups!