A CHIMPANZEE could have spent ten months plotting her daredevil escape at a North Yorkshire zoo, according to an independent inquiry.

But the ape's bid for freedom ended in tragedy, when she was shot dead by a Flamingo Land marksman.

A Government inspector was called in to investigate last December's fatal shooting, after the chimp scaled the wall of her enclosure.

Expert vet Michael Fielding has now recommended a range of new security measures to close off the animal's escape route.

Meanwhile, Ryedale District Council launched its own inquiry, to find out how the chimp managed to get away.

Ryedale's environmental health chief Steven Richmond said the chimp enclosure was surrounded by a moat and a 5,000 volt electric fence - so the chimp could only have escaped upwards.

She is believed to have climbed up a flat steel door by balancing on its hinges and bolts, to reach a tiny defect in the wall. From there, she swung on to overhanging guttering, and propelled herself on to the roof.

Hearing the patter of chimp feet above him, the animal's keeper raised the alarm and the zoo was locked down, with staff evacuated and perimeter gates shut and manned. The zoo was closed to the public at the time.

The chimp dropped down on to a lower roof, walked across open ground and climbed a metal column supporting a monorail track.

A three-man animal capture team was mobilised to coax her down, but she wandered off and became lost and frightened in thick fog.

She was eventually spotted two hours later on top of the lion house.

In his report, Mr Richmond said: "The zoo vet attempted to tranquilise the animal using the dart gun, but the animal reacted badly, became aggressive and the health and safety of the three individuals was compromised. To avoid injury to human life the chimpanzee was shot dead."

Since that day, the chimp's three companions have been kept indoors, and are said to be coping well with their loss.

Zoo bosses have rearranged the door's hinges and bolts, and installed a large metal overhang on top of the wall, with no handholds.

Mr Fielding has recommended further changes, including adding mirrors or CCTV cameras to keep the chimps under surveillance.

He said: "Chimpanzees are extremely strong and physically agile.

"They also, to a larger degree than most other zoo species, have a degree of reasoning capability which allows them to seek out and learn any weak spots in working routines or enclosure fitments.

"Having done so, they will at some time exploit this knowledge - with varying consequences."

The chimp had been at the zoo ten months, but had shown no sign of scaling the wall.

Mr Fielding said the zoo's management of the incident had been "soundly based", while Mr Richmond said the decision to shoot was "difficult but understandable".

Flamingo Land is currently closed. It reopens tomorrow.

Updated: 09:38 Friday, March 31, 2006