Heathrow expansion ‘is threat to England’s largest surviving medieval barn’

Exclusive: campaigners warn 600-year-old New Barn at Harmondsworth could be ‘shaken to pieces’ by vibrations

Six hundred years after it was built, England’s largest surviving medieval timber-framed barn could now be “shaken to pieces” by aircraft vibrations, campaigners warn.

The public has until 1 September to submit objections to the Heathrow airport expansion, which could threaten the survival of the New Barn at Harmondsworth, considered a remarkable example of medieval architecture.

The barn was built in 1426 and was bought in 2011 by English Heritage, which is staging a major conference in September.

Its significance lies in its extraordinary scale, as well as the near-complete survival of its medieval structural timbers.

It is nearly 60 metres long, 12 metres wide and 11 metres tall, with 13 massive oak trusses holding up the roof. It was described as a “cathedral” by the former poet laureate Sir John Betjeman, who was struck by the size and atmosphere of this magnificent structure.

One of the conference speakers is Justine Bayley, English Heritage’s former archaeological scientist. She told the Guardian that the boundary of the extended airport is barely a few hundred metres from the barn, which “could be shaken to pieces by the vibrations from airplanes taking off”.

The barn was built to store agricultural produce exactly 600 years ago this year. The land had been bought in 1391 by the then bishop of Winchester.

Bayley said: “It’s not plus or minus 10 years or half a century. How many late medieval buildings do we know when they were built? Its structural timbers are more than 95% original. Most of the big medieval barns and other large timber-framed buildings have been repaired, and you’re lucky if 50% of the original timbers are there.”

If the Heathrow expansion goes ahead with a third runway, she questions whether the barn is “still going to be here”.

The government is consulting on amendments to the Heathrow expansion national policy statement, for which it is now seeking comments. It is an ongoing process which includes Heathrow airport running its own consultation later this year.

Bayley, who chairs the Stop Heathrow Expansion campaign, said: “The Department for Transport (DfT) has declared that Heathrow is a critical national infrastructure and therefore all the legislation to do with environmental limits and climate change and so on can be just ridden roughshod over because they’ve decided that it was more important that Heathrow’s expansion goes ahead.

“It bulldozes two villages and makes another two or three uninhabitable. It’s all there in the detail that’s been consulted on. This is effectively the government setting out the hoops to jump through. They’re moving the goalposts.”

Noting that the prime minister, Andy Burnham, has previously expressed concerns over the Heathrow expansion – because the plans divert infrastructure investment “away from the north and traps it in London” – she said that opposing the plans will be “difficult but not impossible”.

She argued that actual measurements of the vibrations from the current north runway have not been taken, although it is a similar distance from the nearby village of Longford, which would be demolished: “Longford has dreadful vibrations. You can stand in a house and feel it coming up through the floors and through your feet. Heathrow was saying ‘no, you’re imagining things, that’s not true’. Just because they don’t want it to be true. If they were to actually monitor vibrations and the noise, that would throw up warnings for the barn.”

Christian Hughes, who understands that his Longford home will be demolished if the third runway goes ahead, fears for the barn’s survival as a relatively new house in a nearby hamlet has developed “significant cracking” from the vibrations of passing aircraft.

He said: “We can actually feel planes departing before we can hear them. The low frequency is so bad. My house is 200 years old. Longford has houses that date back to the 1600s and even older. They’ll be demolished as well. It’s criminal.”

Marian Campbell, art historian and former curator at the Victoria and Albert museum said: “This visually stunning medieval building, the New Barn, is improbably located close to Heathrow’s runways. It is an exceptionally rare survival. Apart from its enormous size … it is exceptional too because documents tell us exactly when it was built – 1426 – where the trees came from and who paid for it.”

A Heathrow spokesperson said: “We will continue to listen to and work with our local communities as we progress our expansion plans, including the opportunity to take part in our own public consultation later this year. While the Great Barn is outside the new airport boundary, the DCO process will look in detail at a wide range of potential impacts and any necessary mitigations, to ensure this crucial project is delivered responsibly.”

English Heritage and the Friends of the Great Barn at Harmondsworth are hosting the conference in the barn and the adjacent church of St Mary on 5 September. It will include papers on the barn’s construction and recent archaeological investigations.

A DfT spokesperson said: “Views on the potential impacts of expansion – including on the environment, heritage sites and neighbouring communities – will be carefully considered as part of our consultation before any final decisions are taken.”