Price, R. v [2024] EWCA Crim 463, May 3, 2024, at paragraph 39:

…there is no need for any hostility when it comes to battery. It suffices that there is the least touching. Although some of the authorities speak of the use of force, there need be no use of force in the sense of violence. The slightest use of force which is inherent in touching will suffice. Accidental touching will not constitute a battery but this will be because there is no mens rea. The intentional or reckless application of any force, i.e. touching, will constitute a battery.