No idea then only official UK specials I know of was the P1, WR1, RB320, RB5 and UK300, Terzo, Catalunya and series McRae but it's none of those.
I found this page on SIDC
http://www.scoobypedia.co.uk/index.php/SidcFaq/SpecialEditions
Maybe it's a:
Prodrive WR Sport
Take the standard Impreza Turbo from new and add the full Prodrive interior treatment, suspension package, body kit, wheels with exclusive WR interior and exterior badging (engine upgrade not compulsory) and an official World Rally Sport limited edition of the Impreza Turbo is yours (for £30,000).