Yes, you are 100% right, i did not read the sign well enough. I also found out about Coventry dome after I posted it to the forum, but with the building year, it doesn't make sense.
The guitar seems to be displayed in the USA (it also mentions Rosemont theater 2001 on the sign). That is strange too, why would it be there 12 years later when the guitar is signed in 1989? And at what occasion was it signed? I would expect that it was signed after on of the two charity shows in 1989 (Egham, Newcastle) and given away or sold for the charity.
I guess it will be one of the ever lasting mysteries...