Thing is, I believe that all the BA flights to HEL (infact all s/haul out of T3) is done by bus. One of the BA staffers posted something about this in the last couple of days but I can't find it. Part of an agreement with BAA so when the Oz flights move in they're guaranteed gates.
Found it -
http://www.flyertalk.com/forum/11978663-post2.html