A mum broke down in tears as she told an inquest how her baby had suffocated to death after falling in a gap between her bed and a radiator.
Louise Fitzpatrick had left three months old Tilly and her twin sister with her then boyfriend while she went shopping.
The inquest heard that the mother's two-year-old son may have accidentally moved the baby from between two pillows which allowed Tilly to fall into the gap, causing her to overheat.
Louise sobbed as she told West London Coroner's Court that Tilly had 'definitely been moved' - possibly when her son, Reilly, had gone looking for toys.
Louise had gone out shopping with her son Jaden, leaving her other children with boyfriend Tim Clark.
However, she became concerned when her boyfriend stopped answering her phone calls. When she went back to her home in Chelsea, west London, she said she had a 'gut feeling' that something was wrong.
"When I looked in the bedroom I couldn't see Tilly at all, and by this time I was shouting at (Tim) 'Where's Tilly?'," she said.
"When I went back into the bedroom I just saw a pink vest and then saw her down the side of the bed.
"I was just screaming and before I knew it Tim was telling me how to resuscitate her from what they were telling him on the phone, and then the next thing I remember is my dad coming in."
Paramedics rushed the baby to hospital where she was briefly revived before being pronounced dead.
Louise told the inquest: "She was definitely moved. There is no way she could have moved from where I left her, she was only three months old.
"After she died I thought about this all the time. How did she get there? I don't know what happened but I don't think Tim hurt her - there's no possible way.
"I believe that if she hadn't got down the side of the bed she would still be here."
Her inquest told the inquest he had last checked on Tilly at about 1pm, but then he fell asleep while feeding her twin sister in the living room and watching cartoons with two-year-old Reilly.
He said: "There's no way she could have moved from between the pillows.
"Reilly was two at the time and the door to the bedroom was a little bit open so I could hear her [Tilly]. "He goes in there sometimes to get his toys so he might have gone in there."
A post-mortem revealed Tilly had been starved of oxygen and must have lain face down for up to an hour after her death. The inquest continues.