If their European tours were infrequent or non-existent before the 91 and 92 tours, I would hesitate to give them much credit...it would have been more the fans being attracted to the event more than the individuals, getting into "the WWF experience" as a whole, anxious to see "The #1 wrestling group!!!" (or insert whatever other WWF hype they spread from 83-present here).
If Europe was a more regular stop in the years preceding it, then that might be a different story.
I wouldnt say the Road Warriors were a huge draw in the UK, more the product itself as stated. There are a few factors in the increase on UK gates, Europe maybe different as Italy and France were visited by the WWF before WWF UK debut in 1989. The one key factor is the rise in Sky subscriptions between 1989 to August 1992, when WWF hit its peak (Although being a young teenager in the late 1990s I would say it was bigger in this country then).
When Sky was launch its no secret that WWF programming was one of the flag ship shows which lead to the October 1989 TV special. WWF didn't tour the UK (I far as I can see) until April 1991, that's 18 months in which time Sky subscriptions in the UK without a doubt grew, there was definitely alot more merchandise on the shelfs (Sticker Books/VHS/Toys) also. Whether tactically done or not, the UK fan base which was growing and growing were waiting for the "WWF Experience" were made to wait for 18 months the Royal Albert Hall show before they saw a show again, while WWF programming was being aired throughout the week. UK rampage came later that year and early the following into 1992. Now we move onto the summer of 1992.
The one major factor in WWF success in the UK has to be the increase in viewers during the summer of 1992, where did these viewers come from, they came from the increase of subscriptions from Sky due to its new carrot, live football. In the summer of 1992 Sky won the rights to show the "New" Premier League, which would of lead to more and more households subscripting to Sky to watch live football, in turn more and more people viewing WWF wrestling which at this time was on 4 times a week, (Superstars, Challenge, All American and Prime Time) which means it was probably the most at the time of any programme was on Sky. UK viewing figures would of gone though the roof almost instantly leading to the decision to run Wembley Stadium.
We're the Road Warriors a big factor in the UK drawing, possibly? I had a pair of LOD trainers, but overall the explosion of the WWF in the UK in the early 1990s draws mainly from the Sky viewership increase. It was perfectly placed on the Sky One schedule, it came after kids TV on Saturday mornings and it was the programme on before amazingly popular Simpsons on Sunday evenings, simply but genius.
I wish I could find the subscription figures for the early 1990s for Sky to back up my argument, but I'm sure someone like John Lister could back this up an even build upon it...