The film crew walked through the open gates

A reporter and a two-man crew were able to walk freely onto the aircraft manoeuvring area through an open gate, to film passengers boarding a flight a little over 100 yards away.

But Sophie Hull and her team were stopped by security staff half an hour later while filming a short sequence in the terminal.

They were questioned for nearly three hours by Special Branch officers before being released without charge.

Unmanned barrier

"It's perhaps ironic they were more interested in what we had filmed and where we had been than whether we posed a threat to passenger safety," said Ms Hull.

"I was amazed at the ease with which we got into very sensitive areas of the airport."

Findings included... Gate allowing light plane pilots to their aircraft was permanently unmanned Airfield perimeter fence ends just 50 yards from a public road Radio frequency used by airport security staff published on the internet

Ms Hull said they had shown their footage to aviation security expert Chris Yates, who was "absolutely stunned" at what he saw.

"This is a shining example of how not to do security," he said.

"I am shocked and totally appalled that it's that easy. They should have better security than this."

Airport officials deny security is a problem and say they have consistently passed tough inspections by the Department of Transport.

The gate used by Ms Hull to enter the airfield has now been closed - although officials say this had already been planned.

Airport Director Rob Goldsmith said: "We have a level of security we're confident about which is geared towards protecting passengers.

"We're confident passengers using this airport can feel safe and secure."

Humberside Airport, near Brigg in North Lincolnshire, is used by holiday charter airlines and has scheduled flights to Aberdeen and Amsterdam.

Sophie Hull's report can be seen as part of Inside Out on BBC One in Yorkshire and Lincolnshire on Monday 5 January at 1930 GMT.