Oxford City and University Walking Tours for Four - Key InfoVoucher Validation Your voucher is valid until 01 Jul 20 You must validate book and use your voucher within the voucher expiry date.Duration: This experience will last approximately 2 hours.Group Size: This experience is for four people there will be other people there on the day.Weather Dependent: NoThere is no minimum age for this experience under 16s must be accompanied by an adult.Availability: This experience is available on selected dates throughout the year.