The battle to construct a third runway has been going on for much longer than your estimate of 31 years (Editorial, 6 June). It first gained government approval as long ago as 1946 but was abandoned by the incoming government in 1952. Since then there have been further attempts and in 2009 it once again gained parliamentary approval. This was overturned by the coalition government one year later when David Cameron declared: “No ifs, no buts, no third runway.” This might have been the end of the matter but the ‘aviation mafia’ is nothing if not persistent and never gives up.

Philip Sherwood

Author, Heathrow: 2000 Years of History, Harlington, Middlesex

• There is one vital element of the Heathrow runway debate that has not been aired this time (again) and is surely the central point. In the 1970s, an energy study warned us of the finite nature of oil-based transport. According to the Institute of Mechanical Engineers in 2016, there are 1.3tn barrels of proven oil reserves left in the world’s major fields, which at present rates of consumption should last 40 years. So if it takes 20-30 years to build the third runway, that means just 10 years of use. And that does not take into account current population expansion rates and the likelihood of greater demand on oil reserves over the next 30 years. A third runway at Heathrow is utterly futile and pointless. Air travel in its current form is dying. We need new solutions, new energy sources – not tired out old arguments.

Nigel Cubbage

Merstham, Surrey

• Climate change is a good reason for opposing a third runway at Heathrow. Air pollution is another. The chief executive of Heathrow, John Holland-Kaye, has circulated local residents reassuring them that he takes this issue very seriously. In fact Heathrow uses diesel generators to refuel around 40% of its planes. It has been offered renewable energy generated locally but turned down the proposal as it was slightly more expensive. So pollution and sustainability do not seem to feature in Holland-Kaye’s business decisions.

Nor it seems in the government’s. The real reason for Chris Grayling’s announcement is that Brexit will free the UK from the EU air quality directive; and we already know that Michael Gove’s new Environment Agency has no regulatory teeth. It can issue advisory notices regarding pollution levels at Heathrow, but the government will be immune from prosecution. Those who have hitherto failed to comprehend the cynical rationale behind Brexit need look no further than Heathrow.

Dr Robin Russell-Jones

Chair, Help Rescue the Planet

• The Guardian continues raking in the ad revenue from flight and travel companies while moralising to us about the impact on the upper atmosphere of all this air travel. Isn’t it time to decide which you believe is more important – planet or profit?

Martin Sandbrook

Stroud, Gloucestershire

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