Just returned from an art tour which was really marred by the amount of pickpockets. 20% of our group had cards/money stolen. Peterhof was the worst, and I think my purse was stolen from a bag at my waist while I was taking a photo!
(My theft was an organised gang as within minutes of the 'theft' they were online and bought £7,500.00 of electrical items)
So do be careful!