Lancashire family hit with £15,000 knotweed bill after buying home in Britain's worst postcode

A small neighbourhood in Lancashire has been revealed as Britain's worst postcode for Japanese knotweed - with one recent homebuyer revealing a hidden infestation will cost him £15,000.

New data shows Whitehall, a small neighbourhood in Darwen, with a population of 9,000, has the highest number of recorded infestations in the country.

The fast-growing invasive plant spreads through an underground network of roots and can wreak havoc on gardens, property values and house sales.

A total of 92 incidences were logged in BB3 2, which sits in Blackburn with Darwen - itself named Britain's worst-affected borough with 2,135 cases, or 40 per square mile - in figures compiled by leading invasive-plant specialist Environet.

Nathan Hannaway, 33, lives with his partner and their two children in the worst-hit postcode, where he says knotweed was concealed in the garden of their £430,000 dream home.

The family stretched their budget to buy the large five-bedroom Victorian semi in the leafy suburb on August 8 last year.

They had moved from a two-bedroom house in Bury and hoped to transform its overgrown garden while creating more space to expand their family.

But soon after moving in, a neighbour asked Nathan whether Japanese knotweed had been discussed during the sale.

Nathan, who runs a wind-turbine testing company, had barely heard of it - so researched its red-speckled stems and walked along nearby riverbanks to see what it looked like.

Back home, he was horrified to spot five shoots in his garden which appeared to have been cut back. A survey by Environet found knotweed growing in three separate areas.

Nathan said: "I was quoted £15,000 to remove it - I was shocked.

"What they found when they excavated was unbelievable. There was so much of it."

He is now locked in a civil dispute with the previous owner, claiming the infestation was not disclosed before the sale.

He said the seller answered "no" to the knotweed question on the TA6 Property Information Form - the document used to give buyers information about a home.

The Law Society's TA6 form instructs sellers to answer truthfully, completely and accurately - warning that misleading information may leave a buyer able to claim compensation.

Nathan said the former owner disputes his allegation and maintains they discussed the plant.

He said: "It was infuriating. I can't really explain how I felt because this house was already way out of our budget.

"When we heard it would be £15,000 to remove - that was a big chunk of our budget for the renovation.

"Everything I wanted to do with the garden is now on hold."

Nathan's neighbour Brian Hartley, 84, said he had seen knotweed appear in his garden during the 30 years he has lived there.

He said: "If you don't stay on top of it, it spreads like wildfire."

Nearby at Blackburn Old Cemetery, fresh clumps have also been cordoned off to stop lawnmowers slicing the plant into fragments and spreading it across the grounds.

Maurice Ffelan, 82, of the Friends of Blackburn Old Cemetery, said: "It's a bugger to get rid of. It can grow to 10ft tall."

It can also grow up to 10cm a day in the summer heat, reaching up to three metres across a single season.

Maurice added: "The problem is if you start mowing it, you transfer little bits about and you don't notice until the next year when it suddenly starts popping up everywhere."

Environet's research includes more than 100,000 verified sightings gathered over more than two decades and is updated by by specialists and the public.

The company says it provides Britain's most comprehensive picture of Japanese knotweed.

Operations director Emily Grant said the Blackburn and Darwen figures were particularly reliable because local residents had meticulously recorded infestations.

She said: "They are the most accurate of every location we have in the UK."

She said many of Britain's biggest hotspots had histories of heavy industry, mining, railways, shipping and large-scale soil movement.

Knotweed was also deliberately planted beside rivers and railways to stabilise embankments.

Emily said: "Japanese knotweed remains a serious issue because it does not respect boundaries.

"The problem is the stigma that tends to be attached to the plant, which can cause financial damage.

"You can be sued by your neighbour if you allow it to encroach into their property. It's definitely not something that you should ignore."

Guidance from Propertymark, the professional body for estate agents, says knotweed is material information which should be disclosed and warns it can reduce prices, delay transactions and cause sales to collapse.

BRITAIN'S KNOTWEED HOTSPOTS

Figures supplied by invasive-plant specialist Environet combines infestations recorded by specialists with reports from homeowners, surveyors, treatment companies and members of the public.

Worst areas by infestations per square mile:

Blackburn with Darwen - 2,135 incidences; 40.36 per sq mile

Bristol - 1,323; 31.5 per sq mile

Bolton - 1,651; 30.59 per sq mile

Brent - 464; 27.8 per sq mile

St Helens - 1,324; 25.15 per sq mile

Cardiff - 1,208; 20.94 per sq mile

Newport - 1,752; 20.86 per sq mile

Haringey - 236; 20.65 per sq mile

Lambeth - 204; 19.39 per sq mile

Nottingham - 528; 18.23 per sq mile