The Shadow Secretary of State for Transport, Maria Eagle, says the Heathrow spur of the high speed rail network would cut down on domestic flights and improve the overall capacity of the airport.
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Police have released an e-fit of a man suspected of attacking her.
The force has been tweeting after carrying out a series of dawn raids.
Adenike Akingbogun made the dangerous manoeuvre after ignoring the crossing lights and driving onto the tracks.