unlawful force implies lack of consent (activities involving implied consent are: bumping someone on a bus, contact whilst playing sports, tapping someone's shoulder to get their attention etc.)
Smith - actual bodily harm is not limited to injury, and extends to hurt and damage so long as it is not trivial or trifling. it is not limited to skin / flesh / bones but all parts of the body including hair
Miller - actual bodily harm includes any hurt or injury calculated to interfere with the health or comfort of the victim providing it is more than trivial or trifling