Zak Bennett-Eko, 22, was arrested by the police in a bar after he confessed that he threw his 11-month-old son into the water.
According to an eyewitness account, he wandered into the pub moments after the boy fell into the water and ordered a drink, and sat there and ‘stared’ according to witnesses.
Paramedics battled to save the boy after he was pulled from the water by firefighters, some 100 yards from the bridge.
A barmaid working at the Lock Keeper told how a man came in and asked to buy a drink, but had no money.
She said: ‘Then loads of people came in screaming that there’s a baby in the river.
‘He sat there and stared, he didn’t move so the police were phoned and he just told a customer that he’d thrown his baby in the river.
‘Everyone was up barring him, he sat there and stared and didn’t move.
‘The police were phoned to say ‘we think we have who you’re looking for”
The baby was taken to hospital but pronounced dead a short time later