We booked well in advance with a special off. We would have been better off to wait until the day before to have a better handle of the weather. The bad weather definitely impacted our tour. Even with a great weather day, we had a guide that was not an expert on London roads/transportation or on Harry Potter. The guide for this tour should be British/English and LOVE all things Harry Potter. The guide did not use headsets and could not be heard over the traffic and other city noise. This could be an awesome tour with the right guide.