A furious pensioner who claims his neighbours built a garden wall which encroaches two inches onto his land has launched a campaign to have it taken down by drilling holes and erecting signs outside his home.
Ewen Taylor, from Cardiff, has accused the family next door of carrying out "illegal building work" after they built an extension to create more dining space.
They removed the garden wall they previously shared and replaced it with a new one – which Taylor claims juts into his own garden by two inches.
"It's a matter of two inches but it's my property," he said. "Even if it was half an inch I would object."
Since then, the 87-year-old has been fined £90 for the criminal damage, after admitting using a drill and hammer to make holes in the wall over a period of around five months.
He also peeled off a strip of stucco from the building extension. Four circles in the garden wall show where the family have sealed up damage.
The mum described the actions as "intimidating" for the children.
Taylor denied being intimidating saying: "I don't see how it was intimidating. Hammering and drilling have been going on next door for years. And that's acceptable. If they want to hang new cupboards up they can hang new cupboards up. My wife would always hear it and say: 'They've bought another box of nails.' She passed away quite a few years ago."
Unhappy with being prevented from drilling the wall, Taylor began putting up signs outside his home, some of which accused the family of being "thieves".
The mum said: "The police took away his drill. That's when he started with the signs. We called the police two weeks ago and they said they can't do anything because it's in his private property. They said it is like a protest sign even though it's got our house number and he's calling us thieves. How can that not be offensive?"
The messages include: "You and your cowboy builder are thiefs [sic]"; "Other councils take down illegle [sic] building work"; "Will they sue me?"; and "Do not like my signs, tell the council".
The neighbours – a married couple with four children aged eight to 20 – deny any encroachment.
The mum, 42, said: "I have no idea why he thinks it is in his property. It is distressing, especially for my children. They are embarrassed to go out when people ask questions about the signs."
"Since we moved in 20 years ago [Taylor] hasn't talked to us," said the mum. "We hadn't had an argument or anything. This is the first time there's been any confrontation.
"Cardiff council says there's no need for a planning application for extensions of six metres and this was within six metres. Then after the work was finished [Taylor] drilled straight through."
The pensioner said he felt he was left with "no other choice" but to drill holes after the council refused to intervene.
One council officer wrote to Taylor that the extension did not need planning permission and that boundary disputes are not planning matters. This would be a civil matter, he told Taylor.
Taylor said he launched his protest because he cannot afford civil action. "I am protesting that they have encroached on my property to extend their property, devaluing my property. I am a victim and I am penalised?"
When asked if he tried to speak with his neighbours about his concerns he said: "Oh no. How do you talk to someone and tell them what they have done is illegal?"
The family said police have advised them they could launch civil proceedings over the display but they decided against it to avoid legal costs.
A council spokesman said it was a civil matter between two parties, adding: "We could only get involved if the signs were on the highway, causing an obstruction, or have been put up without permission, so in effect flyposting, which is an offence under the Environmental Protection Act 1990."
South Wales Police have been approached for comment.