Top politicians have vowed to do all they can to block the plans to build a rail freight terminal on Green Belt land.

The battle to prevent HelioSlough building the £300m interchange has been going on for the past seven years and has cost local council taxpayers nearly £1.5 million.

St Albans District Council challenged Eric Pickles' decision to grant planning permission for the development in Park Street in the High Court this week.

Mr Pickles, the Secretary of State for Communities and Local Government, initially rejected the appeal from developer Helioslough but changed his mind last July.

Following the decision, the council lodged an appeal, which was heard at the Royal Courts of Justice on Tuesday and Wednesday.

Campaign group STRiFE – Stop the Rail Freight Exchange – gathered outside court, joined by their legal representative QC Paul Stinchcombe.

The council’s barrister Matthew Reed told the Honourable Mr Justice Holgate he was challenging the decision on three points of law - the first concerned with the legality of the Secretary of State’s approach in taking his decision.

The second ground for appeal related to the misapplication of wording in the National Planning Policy Framework, a document that sets out planning policy nationally.

The third ground for challenge related to "procedural irregularity and inconsistency" on the rail freight interchange decision.

He also argued for consistency, and told the court that because an incinerator on green belt land at Hatfield had been turned down by the government, then the decision should be the same for the terminal on the former Radlett aerodrome.

HelioSlough said its plans for 12 freight trains, each up to 750 metres long, followed government policies to increase the transport goods by rail.

It further argued the terminal was needed to serve the South East.

During the proceedings, the judge observed that the incinerator in New Barnfield was a quashed decision and described each case citing the other as a potentially “ridiculous ping pong” situation.

The judge said a ruling will be published in “due course”.

Conservative’s James Clappison MP, Anne Main MP, and Oliver Dowden all attended the hearing.

Mr Dowden, prospective parliamentary candidate for Hertsmere, said: “This would be a disaster for us. It would destroy precious green belt, clog our roads with thousands of lorries and after Thamelink's recent disastrous performance, the last thing in the world we need is more disruption to our trains.”

The development over 300 acres of Green Belt land would mean 3,000 extra Heavy Goods Vehicles every day, and 3.5 million sq ft of warehouse accommodation in five buildings.

St Albans MP Anne Main said she was pleased the council was fighting the proposal.

She said: “I was pleased to have joined STRiFE and local campaigners at the High Court.

“The STRiFE team have been tireless and doughty campaigner over the nine years, who have been relentless in their pursuit of common sense.

“It is no small achievement to have kept the fight going and to have consistently raised money for a legal team to do battle in the courts.

“Regardless of how inappropriate we all feel the development is, the decision is going to be made on the finer points of law.

“I and my constituents feel that this whole process has been far removed from local decision-making. Given the length of the campaign, I sincerely hope the judge takes his time to give proper consideration to this very long and arduous fight against an unwanted and unpopular railfreight terminal.”

A decision will be made in “due course” by the judge.