A husband who listened helplessly on the phone as his wife was stabbed to death as she tried to protect their children from an intruder will star in the latest series of SAS Who Dares Wins.

Danny Cross, 40, is featuring in the Channel 4 series which started on Sunday night as he pushes himself to the limit alongside fellow contestants.

In 2015 his wife Nicola Cross was brutally killed as she tried to protect her children from a crazed intruder who had broken into their home in Hemel Hempstead, Hertfordshire.

Mr Cross, an IT specialist, was working away from home at the time and 200 miles away in Hull when, during a phone call with 37 year old Nikki, heard her desperate fight for life.

Pictured: Daniel Cross lost his wife Nicola (together, left) when she was brutally stabbed to death at their home in Hemel Hempstead in 2015. Two and a half years on, the widow is starring in Channel 4's latest series of SAS Who Dares Wins (right)

Marcin Porczynski, then 27 and a schizophrenic, broke into her home late at night on 14 September 2015 intending to kidnap her two young children.

Porczynski later pleaded guilty at St Albans Crown Court to Nikki's manslaughter on the grounds of diminished responsibility and was ordered to be detained in a secure psychiatric unit for an indefinite period.

Killer: Polish warehouse worker Marcin Porczynski is currently detained in a secure psychiatric unit for the murder of Nicola Cross

Since then Mr Cross, who lives in Hemel Hempstead with his two children has been trying to rebuild his life.

Writing on a Facebook page for Nikki's Wishes, which is a fund that was set up by her friends to support her children, Danny has posted a message revealing that he is a contestant in the Channel 4 series.

He urged followers of Nikki's Wishes to tune into the news series of 'SAS Who Dares Wins.'

He writes 'My physical and mental capacities were pushed to the limit and beyond during this unforgettable experience where I learned so much from real life special forces hero's and formed lifelong friendships with my fellow recruits.

'I hope you all watch and enjoy my suffering for your entertainment and the message comes across about speaking out regarding mental health and recovering from tragic and traumatic circumstances in life. Watch and enjoy. Regards Dan.'

In the opening episode Dan and the other contestants are seen jumping out of a helicopter into a lake.

They have to go on gruelling runs and cross a gorge on a rope.

In happier times: Mr Cross, an IT specialist, was working away from home at the time and 200 miles away in Hull when, during a phone call with 37 year old Nikki, heard her desperate fight for life

Since the tragedy, Mr Cross, who lives in Hemel Hempstead with his two children has been trying to rebuild his life (above, the widow featuring in Channel 4 series SAS Who Dares Wins)

Their mental toughness is tested to the limit as they are deprived of sleep.

The name for the fund Nikki's Wishes came from a jar Nikki Cross used for writing and storing her wishes.

Last year, Mr Cross posted on the Facebook page the news that he was training to be a volunteer counsellor with the Homicide Victim Support Service so that he could help other families going through the nightmare of losing someone in violent circumstances.

Writing at the time, he said: 'For me it is essential that I use what happened to my family in a positive way to help other families going through the toughest of times. If I can help them to get to the same point I am now, then I will be happy.'

Mr Cross has urged followers of Nikki's Wishes to tune into the news series of SAS Who Dares Wins

In the past, Mr Cross has raised awareness concerning mental health issues arising from the loss of a loved one and has received the support of James Corden, Rio Ferdinand and One Direction star, Niall Horan

In the past he has raised awareness concerning mental health issues arising from the loss of a loved one and has received the support of James Corden, Rio Ferdinand and One Direction star, Niall Horan.

In an earlier posting on Nikki's Wishes, Dan wrote: 'There has been a lot of press lately about mental health awareness, especially within men and the armed forces and also, thanks to Rio Ferdinand, a fair bit about how widowed men cope when losing your spouse at an early age and with very young children.

'For us, mental health is at the forefront of pretty much everything surrounding our situation, from the person who murdered Nik, who was diagnosed with Paranoid Schizophrenia, to myself and my children, who suffered with Post Traumatic Stress Disorder(PTSD), anxiety and depression both in the immediate aftermath of Nik's death and how evident it still is today particularly within my son and myself.'

'Getting professional help for these symptoms is essential and we would not be where we are today without the fantastic counselling we received from Dr Jill Mack from 'Assist Trauma Care' who was assigned to us via the Homicide Victim Support service with whom I am now a volunteer.'