The heir to an eye-watering £230 million fortune had confided in his psychiatrist that he attempted to break into Buckingham Palace just one month prior to carrying out a brutal killing.
Dylan Thomas, 24, is the grandson of pie tycoon Sir Stanley Thomas, and had tried to scale the 14-foot perimeter fence of Buckingham Palace after he wondered what the consequences would be.
Eventually being hauled down by armed police, the 24-year-old was released on bail before going on to gruesomely kill housemate William Bush in a fit of rage.
Appearing virtually before Cardiff Crown Court today, Mr Thomas denied the charge of murder, but has already admitted to a lesser charge of mansluaghter.
At the hearing, Mr Thomas therapist, Dr Panchu Xavier, took to the stand to provide evidence of the 24-year-olds mental state at the time of William Bushs death.
Dr Xavier, who is a consultant forensic psychologist working at the Ashworth Hospital in Liverpool, told the court how his patient explained the attempted Palace break-in.
In Dylans mind he was trying to understand some of the energy fields of the connection between Buckingham Palace and Cleopatras Needle, Dr Xavier stated.
He could not or would not act appropriately when asked to get down. He didnt understand the significance, and looking back he said it was a silly thing to do.
Dylan Thomas, 24, confided in his therapist Dr Panchu Xavier how he attempted to break into Buckingham Palace just a month before killing his housemate
The court has also heard how William Bush, 23, (pictured) had previously barricaded himself into his room as he slept after Thomas allegedly talked of killing him only two months before the fatal assault
Dylan Thomas attempted to scale the 14-foot tall perimeter fence which surrounds Buckingham Palace before being hauled down by armed police
Cardiff Crown Court also heard how from Dr Xavier how in his opinion, Mr Thomas was exhibiting multiple signs of psychosis in the lead up to the killing of William Bush.
Discussing his attempted scaling of the Buckingham Palace fence, Dr Xavier told the court how Mr Thomas believed that officers on the scene were able to see his thoughts, which in his view was a psychotic symptom.
The psychiatrist was then asked if he believed the theory that Mr Thomas had killed Mr Bush due to his moving out of their shared accommodation to live with his girlfriend.
In response, Dr Xavier stated: Thats not my view. Dylan has not mentioned that being relevant to having done what he has done.
The court was then told of further psychotic tendencies displayed by Mr Thomas, including his attempts to sue retail giant Primark after hearing a loud high pitched squeaking from a stores escalators.
Dr Xavier then told the court that it was not uncommon for people with psychosis to arm themselves if they somehow believe they will be harmed.
Mr Thomas believed in some way that he was going to be harmed, that is his account, Dr Xavier said.
In addition to this, the psychiatrist revealed that Mr Thomas was worried about cocaine being planted on him during his arrest over the killing of Bush.
Mr Thomas has been through a lot of stressful situations and that can precipitate some of the symptoms described, Dr Xavier added.
Mr Bush suffered 21 wounds to the neck after Thomas (pictured) allegedly attacked him with two knives, severing his jugular vein
Mr Bush was about to move out of the shared house where he lived with Thomas into a home with his girlfriend Ella Jeffries
Dylan Thomas is the grandson of pie tycoon Sir Stanley Thomas (pictured) and the heir to an estimated fortune of £230 million
Having been released on bail following his attempts to break into the home of the Royal Family, Mr Thomas returned to Cardiff where he lived with friend William.
The pair had met as schoolboys at £13,000-a-term Christ College in Brecon where they were both students.
Mr Bush had been described as popular amongst friends during their school years, whereas Mr Thomas was regarded as something of a loner.
Cardiff Crown Court was told that Mr Bush had been Mr Thomas only friend but that he had planned to leave their shared house in the New Year to move in with his girlfriend.
Then, on Christmas Eve last year, Mr Thomas brutally stabbed Mr Bush 39 times in the neck and trunk resulting in fatal injuries for Mr Bush.
The court also heard that Mr Thomas had carried out an internet search on the anatomy of the human neck prior to the vicious attack on Mr Bush.
Having spent the night at his Grandmothers for a family dinner on December 23, Mr Thomas had her drive him back to his shared residence in the Llandaff area of Cardiff.
It was hear that he attacked Matthew from behind with a large kitchen knife and a black flick knife.
The court had previously heard how Mr Bush had been sleeping in the house with his door barricaded in the lead up to the stabbing after Mr Thomas had confessed to him that he had thought about killing him.
Dylan Thomas appeared before Cardiff Crown Court (pictured) today virtually. He has denied a charge of murder but already pleaded guilty to a lesser charge of manslaughter
Emergency services at the scene of the stabbing near to Llandaff Cathedral, Cardiff
Flowers left outside of the newly-built house in Cardiff where Dylan Thomas allegedly murdered his friend William Bush
Mr Bush initially escaped Mr Thomas, but the bloodied 23-year-old collapsed on the patio outside the pairs home in front of shocked Christmas shoppers in the busy Cardiff suburb.
Witnesses frantically dialed 999 when they saw Mr Bushs horrific injuries, but Mr Thomas had already called emergency services for his own injuries.
Police arrived on the scene and performed CPR on Mr Bush, with Mr Thomas allegedly telling the startled officers: Hes dead, I have f****** disarmed him. I killed him. He came at me and I stabbed him. He attacked me. It was self-defence.
Paramedics then rushed Mr Bush to the nearby University Hospital of Wales, but he was declared dead a short time after arrival at 12.10pm.
A post-mortem examination carried out by Dr Richard Jones at the same hospital recorded cause of death as multiple stab wounds to the neck and trunk.
Mr Thomas was then arrested in the back of a police van on suspicion of murder, a charge which he denies.
The 24-year-old has though admitted to a lesser charge of manslaughter, with the two-week trial set to continue tomorrow.