I think there will be a tiara. I think that lots of the "breaks with tradition" are going to turn out to be tabloid rumour. The press have been so adamant there would be no Dukedom (even the BBC commented on it when announcing it!), that she would be Princess Catherine etc etc. I think it will turn out to be much more traditional that we've been led to believe.
It'd be lovely to see her in the Cambridge tiara.
It'd be lovely to see her in the Cambridge tiara.