A former flood warden has slammed the Environment Agency for publishing “false” historic flood maps of Marlow and Bisham, saying it could affect the saleability of homes and businesses that were recorded to have flooded but actually did not.

Mike Post, who lives in Marlow, said he noticed a “comically inaccurate” map of the 2014 flood outline in Bisham and Marlow had been published in connection with a flood risk assessment for a planning application in Bisham.

Mr Post said both All Saints Churches had been “wrongly” shown to have flooded, as had a number of other Marlow business and properties, including his own.

He said: “When I pointed out the ludicrous errors in the map to the Environment Agency (EA) they responded as follows: ‘We do not believe that there have been errors in the record of the 2014 flood outline.’

“An historic flood map is an important document – what prospective buyer would believe me in 20 years’ time if I say that my property did not flood in 2014 – it has never flooded – but there is an official Environment Agency map that records that it did?

“I am very concerned that they are happy to publish incorrect flood maps.

“It is quite extraordinary and outrageous.”

Mr Post’s claims come as the construction of new £8.5 million flood walls are expected to complete at the end of this month.

The flood relief scheme in Gossmore Lane and Pound Lane was put in place to shield Marlovians from a repeat of the devastating floods in 2014 and started taking shape more than five years after it was approved.

Speaking about the scheme, Mr Post said: “Not only are property values and saleability affected by such incompetence by the Environment Agency but also it is quite possible that flood defence schemes costing many millions of pounds are based on erroneous surveys.

“The Environment Agency claims that the flood defence scheme at Gossmore Lane will not cause flooding to be worse on the other side of the river along Quarry Wood Road in Bisham.

“Why should we believe them?”

The EA said the historic flood map for 2014 for Bisham is based on laser mapped – Lidar – data and a review of the data is underway to make sure it is “as accurate as possible”.

It has also agreed to update the maps to reflect the 2003 floods.

It said in a statement: “Marlow has a long history of flooding, which is why we are working with local councils to build an £8 million flood scheme to protect hundreds of homes in the town.

“We update our flood risk maps every three months with the best available data and use them as part of our planning – but final decisions about where we build new flood schemes are made with the local community, taking into account other potential sources of flooding.”