The body of Paul O’Brien, 42, who served in Northern Ireland and the Gulf, was only discovered when council workers eventually moved the vehicle to take it to be crushed.
The vehicle had been parked behind the Lazy Otter pub in Stretham, Cambridgeshire since October last year but despite the landlady reporting it to the police three times, officers failed to investigate it.
Mrs Gwinnett also repeatedly tried calling a mobile number on the side of the van but without success.
She claimed the Cambridgeshire Constabulary told her because the vehicle was parked on private land it was not a matter for them but for the local council.
When council contractors arrived in February to move the van, they finally discovered Mr O’Brien’s remains in the rear.
Annette Gwinnett, owner of the public house said she was horrified when she realised there had been a body in the vehicle all that time.
She said: “We phoned the police three times telling them about the van and called the mobile number on the side of it but got no answer.
"We tried and tried and eventually the phone must have turned off. That raised our suspicions and we called the police again. They said it was private land and not their problem and told us to phone the council.
"If we hadn't done that the van might still be there and the family would not know what happened. We did everything we could. It is so tragic."
A spokesman for South Cambridgeshire District Council confirmed the van was taken away by its contractor Charlton Autoparts near Sawston, Cambs on February 25.
Owner Terry Charlton said: "I was the one who found the body and it was very unpleasant and upsetting as you can imagine."
An inquest has been opened and adjourned into Mr O’Brien’s death but it is not thought there are any suspicious circumstances.
His funeral was held close to his former home in Newcastle upon Tyne on March 13, two days before he would have celebrated his birthday.
A friend, who asked not to be named paid tribute to Mr O’Brien, describing him as a kind man who had served with distinction in the armed forces.
He said: "Paul was a kind man. When he was in Northern Ireland he was on a reconnaissance mission into southern Ireland and came under attack. His best friend was killed but they couldn't bring a helicopter in to pick them up. Paul carried his body for five miles to the border."
A police spokesman said: "We did receive a report of concern for the man in January after he had not been seen since November. The handling of that report is being reviewed and the findings will be passed to the coroner for inclusion in the inquest.
"At this stage the matter has not been referred to the Independent Police Complaints Commission."