When Kim and John O'Shea returned home from holiday they were knocked back by the sight of 6ft-tall spiked metal railings extending halfway across the bottom of their back garden.
But the O'Sheas are not alone 15 other residents in Appleford Road, Sutton Courtenay, now see the fencing when they look out of their homes.
The barrier blocks access to a lake in a former gravel pit that has been open to residents for at least 50 years.
Now the neighbours have formed a residents' association to fight developers who have bought the lake from Harwell-based UKAEA and are taking legal advice on how to get the fence removed and regain access.
Mrs O'Shea said: "We got home from holiday and couldn't believe it. Not only that, we have received a letter telling us that we should take down part of our lattice fence, because the new owners say it encroaches on their land.
"We erected our fence 18 years ago, following the line of a fence put up in 1934. Our fence will be staying exactly where it is."
Residents said they were given only two days' notice of the plan to erect the metal fencing.
Jim and Sylvia Howe said: "We can't get out to walk round the lake any more. Why did they have to use such horrible fencing?
"We're really upset and angry to find this ugly fence at the bottom of our garden."
Another resident, Jennie Corrigan, said: "Sixteen homes have had their access blocked off by ugly, dangerous metal fencing, with spiked tops that point inwards to prevent us from getting out.
"It's dangerous, more suitable to a prison. My wooden garden gate opens up to the fence.
"What also angers us is the speed with which all this has been done.
"I understand it's to do with health and safety and insurance, but no-one is clear. Only two days' notice by letter and no attempt at consultation. It's appalling.
"Not only do we want our access to a natural beauty spot restored, we want an apology."
The new owner, whose identity is not known, bought the lake last year.
The land is being managed on the new owner's behalf by the property and estate management firm Pavillion, based in Wheatley, which put up the metal fence.
Residents were told in a letter from Robert Hutton, of Pavillion, that his firm understood a number of issues regarding access were likely to be resolved in the near future. There were other issues about safety.
Mr Hutton writes: "For this reason and until all such matters are resolved we will, in the near future, erect a new fence along our boundary and adjacent to the rear of your property."
Mr Hutton is on holiday and Pavillion said there was no-one else available from the company or the owner of the land to talk about the issue.
Sutton Courtenay Parish Council clerk Linda Martin said that the council understood the residents' concerns but it was a private matter.
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