When Paul Westerman suffered a minor knee injury during a game of tennis, he had no idea the knock would leave his life hanging in the balance.

But just three weeks after the incident - and days before he was due to get married - he fell to the floor of his en suite bathroom and stopped breathing.

"All I remember is looking at myself in the mirror over the sink and being confronted by a ghost," he said. "My skin was grey and waxy, and my eyes looked hollow."

The 44-year-old managed to utter the words "I don't feel very well" to fiancé Ellisa before he collapsed.

He had suffered a massive pulmonary embolism (PE), the result of a deep vein thrombosis (DVT) which was sustained in the deep veins of his lower limb after his tennis injury.

The DVT had travelled through his veins, through his heart and filled his lungs with a deadly blood clot.

"All I can remember is slipping in and out of consciousness, feeling like I couldn't breathe, hearing Ellisa screaming 'don't leave me, stay with me' and one of the paramedics say, 'we are losing him again'," he said.

Paul was taken to Hospital where an ICU consultant offered Ellisa a bed for the night.

Paul said: "What the doctors and nurses were trying to say to her - in the most tactful of ways - was 'Paul will not survive the night. By morning he will be dead. You need to stay'."

The road to recovery has been a long one.

In fact, Paul, from Catworth, has had to accept that his life will never be the same again.

Over the last seven years he has suffered from post-traumatic stress disorder, experienced survivor guilt and battled severe clinical depression.

He has had surgery to remove damaged veins and still has regular visits to the hospital for scans and tests.

He said: "Most people do not survive from a massive pulmonary embolism. The reality of surviving is that my lungs and heart will never fully recover, the deep veins in the injured leg will never assist the natural blood flow and I will be on medication to keep me alive for the rest of my life.

"Facing this reality has not been easy. But I have had the love and support of Ellisa and I also have a purpose - to try to boost awareness about this condition and do whatever I can to prevent others from going through this nightmare."

In 2013 Paul became a trustee of Thrombosis UK and in 2014 he was appointed as a committee member of the National Institute for Health and Care Excellence (NICE) in its examination of thromboembolic diseases.

Last year he joined a pulmonary embolism study (initiated by the NCEPOD), working to identify avoidable and remediable factors in the management of patients diagnosed with pulmonary embolism.

He is now working on a product with medical backing which he believes will drastically reduce instances of DVT.

"I believe I survived for a reason," he said. "And I plan to make it my life's work making sure other people survive too."