He once crewed Royal Air Force sentry aircraft, helping to keep the peace over the skies of Bosnia during the devastating war there.

But after returning home peace was one thing Graeme Sadd struggled to find, and he was diagnosed with Post Traumatic Stress Disorder (PTSD) in 2016.

Now Mr Sadd, 56, is planning to cycle 10,000km throughout 2018, and hopes to raise £10,000 for the charity Combat Stress while he is at it.

Mr Sadd said mental health issues were often overlooked because they could not be seen.

He said: 'Many veterans are crippled by mental health, just as many are crippled with physical injuries. Combat Stress aims to help veterans come to terms with their condition and allow them to lead a better, healthier more engaging life.'

Mr Sadd spent 23 years in the RAF, serving as a radar and computer technician on the E3D Sentry aircraft, based at RAF Waddington in Lincoln. He was part of the Nato force which helped bring peace to the former Yugoslavia during the 1995-1995 Bosnian War.

He left the service in 2001 and spent the next eight years as a police officer, and was stationed at Holt, Cromer, Aylsham and Fakenham stations.

Mr Sadd, who now lives in France, said he was still learning to live with PTSD, and the cycle challenge was a part of his recovery.

He said the goal meant he had to cycle an average of 27km every day of the year.

He said: 'My aim is to try raise £1 for every kilometre cycled.'

Although mental illness is common among ex-service people, many, including Mr Sadd, do not even realise that they are suffering from it or are afraid to admit that they have a problem. The charity Combat Stress addresses these issues and helps service personnel regain a near normal life again.

As part of the challenge, Mr Sadd is planning to take part in this year's London Nightrider - a 50km or 100km charity cycle around the city which takes place overnight on June 9-10.

The ride passes landmarks including Tower Bridge, Covent Garden, St Paul's Cathedral and Abbey Road Studios.

To donate to Mr Sadd's fundraiser and follow his progress, visit www.justgiving.com/graemesadd

See www.combatstress.org.uk for more about the charity.