An engineer who cut the steel plate base of a lamppost was "utterly horrified" when it later fell and killed a baby, an inquest has heard.
The lamppost fell on a pram carrying Tommy Hollis near Chiswick Town Hall, west London, in February 2010.
Tommy suffered brain injuries and died a day before his first birthday.
West London Coroner's Court heard Kelvin Elmore thought the plate was an obsolete tram track and was unaware the lamppost was not secured to the ground.
Tommy suffered severe brain injuries and died two days after the incident in which another woman, Mary Gregory who was pushing her granddaughter in a buggy, was also injured.
In a statement read in the court, Mr Elmore, a civil engineer working with McNicholas, said the plate - 18in from the lamppost - was cut five days before the incident while clearing the area to lay new cables.
He said: "As a father myself, I cannot express how horrified I am to have had any connection with the death of a child.
"If I could take the place of that child, then I would."
Mr Elmore, who admitted to cutting the plate, said: "I simply thought it was part of an obsolete part of steel track and had no idea it was connected to the lamppost.
"I was surprised and shocked how the lamppost had been manipulated to anchor it in the ground."
In his 17-year-career Mr Elmore said he had never seen a lamppost secured in such a way. He was found guilty of gross misconduct by his company and given a written warning.
The court also heard from Health and Safety Executive inspector Dominic Long who said the "hybrid column" used to support the lamppost was "rare".
The inquest also heard from Tommy's nanny, Anna Martin, who said they were waiting at traffic lights when she heard a "hollow noise" and a scream.
In a statement Ms Martin said: "There was a terrible scream and I immediately pulled the pushchair back."
But the buggy had been hit. She said: "Tommy looked like he was sleeping. It had all happened so fast.
"I didn't know what was wrong, but his eyes were closed and he looked like he was sleeping, which worried me. I shouted for help."
Mrs Gregory was also hit by the lamppost and needed hospital treatment. It was her scream that the nanny heard, the inquest was told.
The hearing continues.