Huia, the draw of the show is that the groom is (conventionally) much less involved than the bride and her family.
I wondered how, in NZ, anyone might think "Don't tell the bride" is "normal".
I apologise if you had been led to believe that the UK normally does it like this.
When I said: Just a few minutes watching the show and I'm sure you can tell it's a very odd and unusual way to do things, what I actually meant was that the reactions of family and friends give it away. The dress shop owners, florists, venues (etc) are astounded when the groom says that this is what they are doing.