The five-bedroom, three-storey property was part of a 48-strong scheme called Tors Reach, completed in 2015 by Bovis, one of Britain’s biggest housebuilders.

But Ms Leonard’s bucolic fantasy rapidly crumbled. She is about to spend her third winter in a cold house with a damp lower ground floor and faulty heating system. She has suffered a hotchpotch of building mistakes, bad practice and shortcuts, with brickwork scuffed by scaffolding, metal screws rammed into plastic pipes and gaps between the guttering and the outside wall that could allow water and insects to creep in.

The surface problems were apparent as soon as she moved in. “Doors weren’t shutting properly, including the front door, the garden wasn’t turfed, and it was very badly painted, but the Bovis site manager just told me to ‘make a list’,” Ms Leonard said.

She had bought off-plan but was reassured by the Buildmark warranty issued by the National House Building Council (NHBC).

The warranty – which is presented as a regulatory stamp of approval for the quality of most of Britain’s newbuild homes – dictates that any structural problems found in the first two years will be dealt with by the builder. From years three to 10 the NHBC takes over repairs.

When relations turned sour with Bovis Ms Leonard turned to the NHBC, which describes itself as the “leading standard setter for new homes”. Far from having her building defects rectified, however, she found her living conditions deteriorating further.

The NHBC first investigated Ms Leonard’s home in July 2016 after Bovis washed its hands of the case and agreed that there were 60 issues to be resolved. The first set included repair work to substandard brickwork using the NHBC’s contractor. But Ms Leonard said: “Due to poor workmanship I had to advise the NHBC that I no longer wanted them in my house. The brickwork looked better before they started to make good the damage.”

More repairs were agreed a month later. An NHBC report showed that coping stones on the balcony were marked and stained and very untidy in appearance. It wasn’t until April 2017 that the NHBC took the coping stones away and removed the glass barrier from the balcony. The stones and the barrier have not been replaced. “It’s an accident waiting to happen,” said Joe Ward, her ex-husband. Rather than a vista of rolling countryside, Ms Leonard now looks out over abandoned scaffolding.

“There are a lot of defects in my home and both the speed and skill of the NHBC contractors leave everything to be desired,” she said. “My health has been affected by this experience, I am on antidepressants and sleeping pills and have had counselling. I feel terribly let down by the whole rotten newbuild and regulatory system. The NHBC allowed a home with breaches of building regulations to be put on the market and sold.”

The public impression that the NHBC, which has 80pc of the warranty market, is an ombudsman of quality rather than an insurance company is compounded by the marketing of developers such as Taylor Wimpey. “The NHBC was established over 60 years ago and is the independent regulator for the new homes industry,” the firm’s website read until this summer, when the word “regulator” was suddenly dropped.

Despite its own branding as “dedicated to housebuilding standards”, the insurance mutual bounces culpability back to the builder. “Ultimately the quality of new homes is the responsibility of builders,” it said. “Our priority is to help builders minimise defects in the homes they build and to enable us to provide the 10-year Buildmark warranty to help when problems emerge.”

In a written statement apologising to Ms Leonard the NHBC said: “There are rare circumstances where complex cases can take longer to resolve than we would wish and unfortunately there have been delays in carrying out repairs. It is also clear that some of the remedial works have not been carried out to the high standards we expect of our contractors.”

Maria Miller, the MP for Basingstoke and vice chair of the all-party parliamentary group for the excellence of the built environment, has questioned both the role of the NHBC and its relationship with the construction industry.

“The warranty system is broken and the NHBC has failed the consumer year after year, leaving some buyers dissatisfied with the biggest purchase of their life. The only way to resolve a dispute now is to get an MP involved. We need to rectify the balance of power between customer and construction industry,” she said.

The Conservative MP called for a new ombudsman to regulate the warranty industry. Her concern followed reports this summer that payments flowed between developers and the NHBC.

The most significant of these “premium refunds” was £2.7m to one developer in 2012, while last year the biggest single payment was £750,000. This calls into question the independence of the warranty system, especially when nearly a fifth of the members of the NHBC governing council are also on the board of builders such as Bovis and Barratt.

The NHBC said premium refunds were a way to reward a developer’s good claims history and were not uncommon in the insurance industry.

Paula Higgins, chief executive of the HomeOwners Alliance, said: “There is a definite requirement for a new homes ombudsman or regulator that would act in the best interest of buyers – not the industry – to ensure that consumers are protected and our homes meet the standard that is expected.”

This month the NHBC offered Ms Leonard a £10,000 cash payment to fix the outstanding defects herself. But she said: “The only offer I will accept is for Bovis or the NHBC to buy back my home. For every mistake we uncover there are more behind it and repair costs could escalate quickly.”