I tried to verify this too, because it is very odd that they don't have a reference for it on wikipedia - it should be easily to find a link to the results of an international championship competition.
As far as I can tell, there was no long-distance triathlon european championship in 2004. There WAS a 2004 long-distance triathlon world championship held in Sater, Sweden, but Robert Young is not listed in the results.
Here is a listing of events from the European Triathlon Union. You can look through a few pages to see all events listed for 2004. There is no long-distance triathlon european championship listed. There are, however, long-distance european triathlon championships listed for 2003 and 2005. Maybe a european championship was not held in 2004 because a world championship was held instead?http://etu.triathlon.org/results/P810
2003 and 2005 long-distance european championships:http://www.triathlon.org/results/event/2003_fredericia_etu_long_distance_triathlon_european_championchipshttp://www.triathlon.org/results/event/2005_sater_etu_long_distance_triathlon_european_championships
2004 long-distance world championship:http://www.triathlon.org/results/event/2004_sater_itu_long_distance_triathlon_world_championships
Is there some other long-distance european championship?