The link makes sense with or without a third runway, Thames Valley Chamber of Commerce’s RUTH BAGLEY tells JAMES ABBOTT

The UK’s only international hub airport boasts Heathrow Express, TfL Rail and the Piccadilly Line for rail linkage to the centre of the city – but unlike competitors such as Schiphol or Charles de Gaulle, it has no rail services in other directions. There are coach and bus services linking to stations with services that reach elsewhere, but these are not as attractive as direct rail links.