Do I need to pre-book entry with my Merlin Pass? Yes - Merlin Passholders must click here to pre-book entry. Every Passholder in attendance must pre-book their admission and present both the reservation and their valid Pass at the entrance. Related articles Are there restrictions for using a Merlin Pass at The London Dungeon? How can I purchase Merlin Pass Friends & Family Tickets for The London Dungeon? What if I'm running late for my time slot? How do I contact your Customer Services team? I have Sun Free tickets but I can’t book for the time slot/date I want, as it is showing as unavailable. What do I do?