Dear BAA,
In your quest to make more money each day from 'retail experiences' rather than from aviation - which is supposed to be the industry you operate in - I believe you may have missed a 'retail experience' opportunity.
To further 'enhance' the overall Heathrow experience, why not allocate some of the open air roof space on the car parks as designated 'open smoking zones'. You could charge a tidy sum, and have a dedicated 'smoking retail' outlet located nearby. Just think of the money.
You could describe this in your advertising, as;
'yet one more Heathrow 'enhancement' brought to you, the passenger, by your friend BAA'.
Marvellous.