My DD has been at the senior school for a few years and is very happy and she and her friends have had no serious problems with bullying. Having said that she has a relatively small group of friends who she chooses to be with, some of whom she has known since the prep school, who are all lovely and very supportive of each other. My DD acknowledges that she finds some of the other girls a bit challenging to be around because they like to have a dig whenever they can, so she started off avoiding them but now has the confidence to stand up for herself or laugh at them, (my suggestion!) Annoying, but not bullying. In my experience the sporty girls can get a bit 'alpha' and my DD's academic, not sporty. We also deliberately restrict our DD's access to Social Media, which I think is often where bullying can go undetected. The school IT dept are pro-active and give parents very through info about what is appropriate to have at what age.
The confidence and maturity she has developed at St Cats has been incredible and I don't doubt she would feel empowered to speak up if she had serious problems in the future.
I live locally and know lots of parents with girls throughout the senior school and I know some of them have had problems with bullying, but I don't believe it is a 'big problem.'
I thought the head mentioning it in the newsletter was transparent and helpful - she acknowledged they had uncovered a problem, discussed lessons learned and reiterated advice to everyone about how to discuss/report it with their DD going forward.
My other DD is at another Guildford girls school and by comparison I believe St Cats is far tighter on encouraging respect for each other and their staff members and I am confident nothing is left to chance with her education and personal development. Since returning after the summer, DD has come home full of beans with so much to tell me about her day, she's extremely happy to be back!