From the CPS website:
"An assault is committed when a person intentionally
or recklessly causes another to apprehend the immediate infliction of unlawful force"
http://www.cps.gov.uk/legal/l_to_o/offences_against_the_person/#a07
i.e. it's not necessary for the Crown to show that there was any 'intent' involved in the action that led to the charge being brought. It's enough to show that the defendant was 'reckless' (as, for example, by throwing a pot to the ground where there was a possibility of causing injury, even though that injury be unintentional).