Full details in the TfL press release at:
http://www.tfl.gov.uk/tfl/press-cent...t.asp?prID=398

It seems passengers travelling between west of Acton Town (Heathrow
excepted) and central London are a bit hard done by - they have to
wait up to 20 minutes at Acton Town, just for the privilege of having
to wait again at Ealing Broadway for another train to take them into
London? Given the short length of the route, surely TfL would be able
to provide a much higher frequency on the Acton Town - Ealing Bdy
shuttle using only a small number of trains. Perhaps they are hoping
everyone living on the Heathrow branch will realise they can just get
a train in the "wrong" direction out to Heathrow and then use HEx?