David Hardy, 64, approached five-day-old Elsie Temple in the biscuit aisle where he thumped her while she lay in her car seat.
Her sister, Libby, seven, was so distressed by what she saw that she asked her mother ‘is she going to die?’
Hardy denied the attack saying he was ‘messing about’ believing the Elsie was a doll and had told Libby that he was going to ‘beat her baby up’, Metro UK reported.
However he has been found guilty of common assault. He will also have to pay £1,400 in costs and fines.
District Judge Sam Goozee said: ‘I’m satisfied you struck out with the intention and knowing Elsie was a baby, not a doll.’
‘He’s rushed over punched her in the face, in the head,’ she told the court. ‘He’s rushed over. He didn’t even look at my pram. He’s kind of lashed out.Elise’s mother, Amy Duckers, broke down as she spoke about what happened.
She described Hardy as having a clenched fist. She said that he didn’t say anything but Elsie started crying immediately.
She described her older daughter, who had been hanging onto the rear of the trolley, as ‘hysterical’.
‘I have just gone in complete shock and Julie has looked at me and was like “has this just happened? Did that actually just happen?” I can’t even tell you how I felt. I just went numb. I didn’t know what had just happened myself.