The cost of keeping the former Manston airport on standby as an emergency lorry park for Operation Stack has cost the taxpayer at least £3.5 million, we can reveal.

The Department for Transport has paid the owners of the 800-acre site £3.539m to prepare and maintain the site in the event of Operation Stack being implemented.

It has stood idle since being placed on standby last September but is continuing to cost hundreds of thousands of pounds in case it is needed.

An investigation by the Thanet Extra has discovered the amount spent between September 2015 to July this year.

The government made payments totalling £810,000 last September – at the time preparation work on the site began – followed by £900,000 in October and then payments in November totalling £930,000 and £92,779.

Then, in December, there was a payment of £137,881.

Following these, the DfT made three additional payments for £148,000 and one for £129,600.

None of the invoices mention either Manston or Operation Stack but the recipient is identified as Stone Hill Park Limited at an address at Discovery Park, Sandwich.

The airfield was equipped with floodlighting and lines painted for spaces, while caterers, round-the-clock security staff and parking marshals are contracted to step in should they be needed.

Toilets and shower blocks have also been put on the site.

There was a storm of protests when it emerged the Manston site was to be used as an emergency lorry park after Operation Stack was implemented for a record-breaking 32 days in the summer last year.

North Thanet MP Sir Roger Gale described it as insane and Kent’s chief constable also voiced reservations.

The Department for Transport said it had worked hard to bring costs down and the present payments were a fraction of what it had been required to pay at the start.

A spokesman said: “We recognise the impact Operation Stack has on roads in Kent and it is only ever used as a last resort.

“We have Manston Airfield on standby to hold lorries and reduce congestion in the event of disruption to cross-Channel services. We have worked hard to keep the cost to a minimum and negotiated reductions in our payments since August 2015.”