Rail freight developers are threatening to sue St Albans district council (SADC) if it ploughs on with house building plans.

Searching to accommodate 15,000 more homes in the district before 2036, SADC pinpointed a 100ha Green Belt site in Park Street for 2,000 new builds.

However, developers HelioSlough have planning permission for a large Strategic Rail Freight Interchange (SFRI) on the same site.

The former Radlett Airfield belongs to neither body - owners Herts county council has expressed a clear preference for housing.

The housing quota has been set by government for SADC’s Local Plan, based on a house buying affordability ratio.

Before SADC decided to progress the site, out of more than 2,000ha proffered up by landowners, HelioSlough director Gareth Osborn tried to influence SADC.

He sent a letter arguing that site would throw the Local plan into jeopardy, causing it to be “inherently unsound”.

SADC ignored his advice and the threats have now escalated.

The most recent letter, written by HelioSlough’s agent Hogen Lovells, says: “If the council continues with a Local Plan process which involves this site as a proposed housing allocation our client will be forced to consider all possible remedies including a possible legal challenge to that process.”

It argues housing could be put elsewhere but that an SRFI must be on that specific piece of land: “The evaluation treats housing and SRFIs as effectively comparable land uses whereas one (the SRFI) has demanding site location criteria which make it not “footloose” and the other (housing) is in relative terms easier to accommodate in a variety of locations.”

If HelioSlough are indeed correct and the Local Plan is not delivered on schedule, the Government has threatened to take control of the process.

This would result in less freedom for local people to decide where the housing should be built.

Planning portfolio holder at SADC, Cllr Mary Maynard, responded: “We will look at the suitability of the land for inclusion in the Local Plan in Green Belt terms.

“We used the same criteria as we do for every other piece of land in the district and it has come out as one of the most appropriate for developments for impact on the Green Belt.”

She said SADC will also be seeking legal advice, adding: “It could just be an empty threat.”

The SRFI plans have a troubled history spanning more than a decade. HelioSlough’s applications were rejected by SADC before being allowed on appeal in 2014 by former communities secretary Eric Pickles.

SADC appealed this decision at High Court and lost.

St Albans MP Anne Main has been pushing for more transparency about how Network Rail would manage freight carriages alongside passenger services on the line.

A campaign group called STRiFE (Stop The Rail Freight Exchange) has also been lobbying to stop the plans.

Despite all this, SADC recently approved the SRFI’s layout, design, access, and infrastructure plans - it could only reject them if they materially deviated from the last proposals, and officers deemed this was not the case.

The contentious site will be assessed at the next planning policy committee on June 12.