Artist Alison Lapper tells how her drug addict son, who died in a hotel room, started smoking cannabis at 11.
Parys Lapper, 19, was found dead at a hotel in Worthing after battling with his mental health.
His death was believed to have been an accidental overdose from his drug addiction coupled with heavy medication from ongoing depression.
His mother remains stricken by grief having lost the son whose birth was a miracle itself.
She believes the combination of low-level cannabis use that began at the age of 11 with an increased sensitivity of his mother's disability through teasing at senior school caused his depression and addiction to spiral.
Nearly two decades ago Miss Lapper agreed to pose heavily pregnant with her unborn son Parys.
The white marble sculpture spent two years on the fourth plinth in Trafalgar Sqaure and was unveiled on September 15 2005 at a public ceremony attended by the artist Marc Quinn and Miss Lapper.
'How amazing would it be to have a sculpture that is going to live longer than Parys and me?
'A sculpture that would be around for a very long time, even when we are not.' I had no idea that Parys would die aged 19,' she told The Telegraph.
She told how from the age of four Parys would ask his mother why people were staring at them.
Initially she would tell him it is because he is so 'beautiful' but as time went on she said: 'Because I am like this, son. And they think I can't cope with you.'
Lapper described his primary school years as happy but the confusion of adolescence mixed with losing a grandmother figure caused him to become more withdrawn.
'It was me and him against the world, it really felt like that', Miss Lapper told The Telegraph.
However the 6ft 19-year-old ended up weighing six stone and was emotionally detached from everyone.
He was sectioned aged 16 and moved accommodation frequently including a unit for anorexics and a hostel for asylum seekers.
Unable to live at home due to escalating violence, he lived in B&B and hotel accommodation where his case worker had a caseload of more than 40 people.
It is estimated his body lay undiscovered in the hotel room for three days.
Police had become woven in Parys's life. In his 19 years he has been knocked over by a car, held a gunpoint and beaten up after a robbery.
In an effort to raise awareness of improved mental healthcare for young people, Miss Lapper contacted YoungMinds two weeks after losing Parys.
The charity aims to provide better healthcare for 14 to 25-year-olds and is calling for the next party leader to ensure a cross-government strategy to establish better mental healthcare provisions for this age group.
The campaign Act Early is to raise awareness of triggers, provide better online support, improved resources for schools and early intervention in every community through drop-in centres.
Miss Lapper said: 'By the time it got really bad, I phoned the authorities and said, 'My son needs help,' but that help wasn't what Parys needed by then. He was treated as a naughty boy.'
She described how drugs complicated the treatment he received and Parys refused to go to volunteer for rehab.
At the age of 18 Parys was unable to even wash himself but his mother was denied a say in his welfare.
Miss Lapper was always told she wouldnt be able to carry a child and said she almost didnt have a baby because of the pressure of people saying 'what if he's like you?'
She is no longer in contact with Parys's father but describes his conception as 'a happy accident'.
'All I ever wanted to do was love him... Sorry, sorry... It's so raw still. I miss him so much. I just want him back,' Miss Lapper said.
At the age of 11 Parys, who was dyslexic, left his small junior school in Shoreham, Sussex, to start at a much bigger academy.
Around this time he learned his half-sister had taken her own life aged 22, his surrogate 'granny' died from cancer despite a glimmer of hope of recovering, and a live-in support worker made an allegation that Miss Lapper was sexually abusing her son - a claim that was investigated and disproved but that took its toll on the family.
By the age of 14 Miss Lapper said 'dodgy' people were knocking at the door and Parys began asking her for money to avoid being 'beat up'.
At 16 Parys's drug use became more serious and he was moved to a special unit of the school.
After leaving with no qualifications he became prone to violence and at the same time Miss Lapper was fully dependent on live-in support workers who were unable to cope with the violent episodes.
She said Parys had no connection with anyone and he needed a male role model in his life after always having female social workers.
Parys was cremated and some of his hair and ashes will now be used to make a diamond wedding ring to wear on Lapper's left toe when she marries her fiancé, Si, next year.