11 Sep 2021
First, Viator is not selling the tour. A company named snikkit.com does. They want you to log on to their web site, do some sort of "activation" to your account, then copy "activation codes" to input box and do it before it expires in 48 hours.
When we arrived to the ticket office in Nottingham Castle, they have never heard of this company nor would they accept the tickets we had purchased. We ended up buying new tickets at the booth.
They are scammers. Stay away from them. WARNING.