Fragments of broken tail-lights, and tracks down the bank led him to believe his ute had been hit by a passing vehicle, which shunted it through the wire fence, down a 75-degree bank and over a 25m cliff, leaving his vehicle at the bottom of Otago Harbour.
There was no sign of the culprit, so Mr Langsbury called police to report the incident, then walked home.
A police investigation began yesterday and a boat was used to search for his vehicle.
In the cold light of day, Mr Langsbury said thoughts of what could have happened flooded his mind.
He said it was very fortunate he was not in the ute, or on the bank below it, when the vehicle was shunted through the fence.
''I have done predator control through that area for the last three years, regularly had the ute parked on the side of the road, and been sitting in it with a spotlight looking for stoats or possums. I'd only hopped out of the vehicle last night because I saw a possum.''
He said his vehicle was parked ''safe and clear of the road'' with its park lights on and he was surprised it had been hit.
At that time of night there was little traffic and at least one and a-half lanes of road were left for other drivers.
''I think it was an accident. Someone probably came around the corner a bit too quickly.''
Senior Constable Lox Kellas, of Portobello, said Mr Langsbury was lucky to be alive.
''It [the ute] would have been travelling fairly quickly down the bank and then it becomes a vertical drop.''
Snr Const Kellas said the vehicle would be recovered within the next few days when the weather improved.
The incident was probably a hit and run, but he was keeping an open mind to the idea it might have been intentional.
Anyone with information about the incident is asked to call Portobello police on 478-0209.
