Muhammad Hassam Ali, 17, was unknown to boy who followed and stabbed him in Victoria Square

A 15-year-old boy who followed a teenager he did not know through Birmingham city centre and stabbed him to death after a four-minute conversation has been jailed for life with a minimum of 13 years.

Muhammad Hassam Ali, known as Ali, was 17 when he died in hospital on 20 January, hours after he and his friend were confronted by two masked 15-year-old boys they had never met as they sat in Victoria Square, drinking hot chocolate and chatting about cricket.