A fireman whose son went missing in Germany has vowed one year on that he will not give up the fight to find out the truth as he renews his appeal for help.

Extreme sports enthusiast Christopher Miles, known as CJ, had spent three years in Norfolk before moving to Austria and vanished on July 31 last year after dropping off two people at Salzburg airport.

His disappearance provoked a poster campaign across the two countries, and the creation of a Facebook group with nearly 6000 members.

And now, having made three trips out to Austria this year, father-of four Nick Palmer-Miles is hoping against hope somebody might be able to break the year-long deadlock and help him find out what happened to the popular 28-year-old.

'The more people that know about it the better. It doesn't mean that someone will find necessarily find him, but it's about spreading the word so if anyone remembered a conversation with him or something that might give us another avenue to explore or let us know something new.

'I will never give up on this and won't let anything get in the way until we've got to the facts.'

Mr Miles had lived at addresses in Speedwell Way, Threescore, Bowthorpe, and Primrose Road, in Norwich before moving to Zell Am See, Austria, in 2006.

It was here that he found a 'dream job' at Austrian transfer company Alpentouristik, and made constant calls back to his father to let him know how he was getting on.

However in the days running up to his disappearance Mr Palmer Miles said his son, who was on medication to cope with diagnosed bi-polar syndrome, had been acting erratically during their conversations.

Police found his minibus parked in a train station in the mountainous region of Ruhpolding, Bavaria, with its lights on and the keys inside.

After countless hours spent trawling his son's diaries and computer for any clues, Mr Palmer-Miles, who lives near Nottingham, said he felt 'numb' about the situation, and did not know whether Mr Miles was dead and alive.

'I've gone to Austria to pound the streets time and time again, and you find yourself staring at people and wondering is that my son? It drives you mad,' he said.

'I'm due to go back in a week and pick up his clothes and skis and things from his flat but at the moment I don't think I'm strong enough to do it.'

However, though he speculated that his son may have had an accident while in the mountains due to euphoric effects of the medication, he rejected outright the idea put by a Mr Mile's doctor and, he says, accepted by local police that he committed suicide.

His inquiries have led to a formal investigation being carried out into the medication being given to Mr Miles and the initial diagnosis of bi-polar disorder. He hopes one will be launched into the local police force too.

Summing up his son's kind-hearted nature, he told of a time when he had just arrived back to England from Austria and was in his father's village at a point when children were just coming out of school.

'He did slacklining, where you perform tricks on a wire, and he set it up between trees and was performing to them and had crowds around him. He was there for four hours, allowing everyone to have a try.

The 48-year-old added: 'He only wanted to make people happy, and when he went to work he said if people had been smiling then his work was done. He never hurt anybody'

•Those with any information can email Mr Palmer-Miles on milesy7@hotmail.com. A new Facebook group called CJ Miles is still missing please help has also been set up.

• Has someone you know gone missing? Call reporter John Owens on 01603772439 or email john.owens@archant.co.uk