Accused: Marianne Willoughby killed her son by squirting morphine into his mouth, a court heard

A mother on morphine accidentally killed her 25-year-old son when she squirted her medicine into his mouth 'for a laugh', a court heard.

Marianne Willoughby was accused of giving her high-strength oramorph - which she was taking to treat knee pain - to Christopher Rowley-Goodchild after he had spent a night drinking with a friend.

The 25-year-old collapsed and died at the family home in Weybridge, Surrey, after taking 'at least four or five' doses of the drug, including one he administered himself.

His mother, 50, is standing trial for manslaughter despite a jury hearing Mr Rowley-Goodchild was happy to take the drug.

When paramedics asked Willoughby, who walks with the aid of crutches, why she had given her son the oramorph, she allegedly replied: 'You know, just for a laugh'.

A post mortem found the 25-year-old died from a combination of alcohol and oramorph.

Willoughby denies manslaughter, saying her son administered the fatal dose himself.

Guildford Crown Court heard Willoughby was taking the medicine, which is morphine-based, for severe pain in her knee when the tragedy unfolded late on June 22, 2013.

Mr Rowley-Goodchild had been drinking with a friend, 25-year-old Kirk Ugle, when his mother joined them at around 11pm.

The court heard that after a couple of hours, Willoughby raised the subject of her oramorph and offered it to the two men, neither of whom had taken drugs before.

'They looked at it and they both decided individually that they would have some,' said prosecutor John O'Higgins.

Willoughby used a 10ml syringe to suck up the drug and then squirted it into the two men's mouths, the jury was told.

Mr Rowley-Goodchild passed out, and his mother and friend put him on a bed.

They thought he was healthy because he was snoring but this later stopped, and they could not get a response out of him and realised he had gone cold.

An ambulance was called at 4.20am, with Willoughby telling the operator she thought her son's condition had been caused by his epilepsy.

She did not initially mention the oramorph, the court heard.

When paramedics arrived, she was 'screaming hysterically' and the crew began performing CPR.

The jury heard that during this time, she told one of the paramedics she had given her son 40mg of oramorph. Police were called and arrived at 5.30am, with Willoughby arrested a short time later.

At the police station, she was overheard saying: 'I didn't force him to have the morphine. I shouldn't have let him have it.'

Giving evidence, Mr Ugle, also 25, said: 'She squirted the oramorph into our mouths. We said we were happy to take it.'

Close: Willoughby (right) is accused of accidentally killing her son Christopher Rowley-Goodchild (left)

Mr Ugle said that as far as he knew Mr Rowley-Goodchild had 'at least four or five' doses of the drug, including one which was self-administered, over a period of a couple of hours.

'It just never occurred to me that it would be dangerous to use it,' he told the jury in tears. 'I never thought that what happened, would happen - not in a million years.

'Never from what we took. It just looked like cough medicine.

'The idea kind of sprung up that maybe we should try some, just for a laugh. He (Christopher) was quite adamant about it. He stood up and said it would be fun.

'I think he felt safe taking it. He wouldn't have done it without me there and I didn't really see the harm in it.'

Graham Trembeth, defending Willoughby, said: 'You didn't see it as a drug like heroin or cocaine, like an illegal drug?'

Mr Ugle replied: 'No. It didn't even feel that strong when we took it.'

Horror: Willoughby was screaming were called to the family's street in Weybridge, Surrey (pictured)

Mr Trembeth asked Mr Ugle why he had not initially told police Willoughby had squirted the drug into their mouths. Mr Ugle said he didn't want to get her into trouble.

Blonde-haired Willoughby appeared visibly emotional and rocked back and forth as details of the case were read out.

Mr O'Higgins told the jury of six men and six women: 'It is the prosecution case that the defendant, who sadly is [Mr Rowley-Goodchild's] mother, provided the oramorph and administered it by literally pouring or squirting it into his mouth.

'What she did was to administer her prescription medication to somebody that she knew was already drunk and to whom the drug was not prescribed.'

In her interview, Mr O'Higgins told the jury she was willing to answer general background questions but said 'no comment' when asked about details of that night.

'The key factual issue in this case is going to be the question of the direct administration of the drug,' said Mr O'Higgins.

'It is the prosecution case that it is not just that Mrs Willoughby made the drug available, brought it into the room, offered it to Christopher or even gave it to him.

'The prosecution case is that she deliberately and directly administered it to him. She emptied a syringe into his mouth.'