Task: Question Answering
Input (English): Passage: Lennon was born on 9 October 1940 at Liverpool Maternity Hospital, to Julia (née Stanley) (1914–1958) and Alfred Lennon (1912–1976). Alfred was a merchant seaman of Irish descent who was away at the time of his son's birth. His parents named him John Winston Lennon after his paternal grandfather, John "Jack" Lennon, and Prime Minister Winston Churchill. His father was often away from home but sent regular pay cheques to 9 Newcastle Road, Liverpool, where Lennon lived with his mother; the cheques stopped when he went absent without leave in February 1944. When he eventually came home six months later, he offered to look after the family, but Julia, by then pregnant with another man's child, rejected the idea. After her sister Mimi complained to Liverpool's Social Services twice, Julia gave her custody of Lennon. In July 1946, Lennon's father visited her and took his son to Blackpool, secretly intending to emigrate to New Zealand with him. Julia followed them – with her partner at the time, Bobby Dykins – and after a heated argument, his father forced the five-year-old to choose between them. In one account of this incident, Lennon twice chose his father, but as his mother walked away, he began to cry and followed her. According to author Mark Lewisohn, however, Lennon's parents agreed that Julia should take him and give him a home. A witness who was there that day, Billy Hall, has said that the dramatic portrayal of a young John Lennon being forced to make a decision between his parents is inaccurate. Lennon had no further contact with Alf for close to 20 years.Throughout the rest of his childhood and adolescence, Lennon lived at Mendips, 251 Menlove Avenue, Woolton, with Mimi and her husband George Toogood Smith, who had no children of their own. His aunt purchased volumes of short stories for him, and his uncle, a dairyman at his family's farm, bought him a mouth organ and engaged him in solving crossword puzzles. Julia visited Mendips on a regular basis, and when John was 11 years old, he often visited her at 1 Blomfield Road, Liverpool, where she played him Elvis Presley records, taught him the banjo, and showed him how to play "Ain't That a Shame" by Fats Domino. In September 1980, Lennon commented about his family and his rebellious nature:. 
Question: What was the name of the person that witnessed the heated scene between Julia and Alfred Lennon?
Output (English): Billy Hall.