Before the big fight, the singer had made a solo trip out of the hotel at 11pm, walking a few yards down the road to meet and hug a girl in her 20s before returning alone.
An eyewitness said it appeared the girl handed over some kind of small package to Miss Winehouse as they hugged.
The singer returned to her hotel room and within hours other guests complained of raised voices, clattering furniture and screaming.
Shortly afterwards, the concierge was called.
Miss Winehouse, who has a history of self-harming, had asked for medical assistance to patch up cuts on her arm.
At around 2.30am, said guests, the fight sounded like it had restarted – then Miss Winehouse was seen sprinting down the corridor to the lift, pursued by her badly bleeding husband.
One guest who got into the lift to reception at the same time said they started shouting at each other. "Amy was in floods of tears. This guy was screaming at her.
"She was cowering in the corner and I thought he was going to hit her. When the lift door opened, she took off across the lobby at a real pace.
"He was chasing after her and was about five paces behind by the time she got to the main hotel entrance."
The couple then dashed into the street.
An eyewitness said: "Just after 3am, Amy came sprinting out and down the road.
"She was in a real state of panic. Blake was running after her, but couldn't catch up.
"Amy was so hell-bent on getting away from him that she ran into the middle of the street and flagged down a random car that happened to be full of girls.
"She was saying, 'Quickly, I have to get in, I have to get away, please help me'.
"Her voice was breaking, you could tell she was scared.
"The car drove off at speed and ended up about a mile away at Charing Cross station. Amy got out and went into a 24-hour shop to buy cigarettes.
"She was looking completely out of her head. Blake ran after the car for a while. He spent the next halfhour or so wandering around in a daze with blood over his face, looking in doorways for her, shouting her name out.
"Eventually, he got through to her on the mobile.
