I don't know much about UK law, but in many states in the US after a period of time, minor offenses can be removed from someone's record. Follow up with you attorney about it.
If everyone in law enforcement complied with UK law, nudists, naturists would be fully at home naked anywhere. Some police officers still make personal decisions that don't uphold the UK law, but solicitors and the courts should not uphold indecency charges were no sexual offence has been committed. If no offence has been committed then no record would exist. The initial problem for the nudist being you must know the law and your rights, because some police officers will try to manipulate interviews to their advantage and get you to admit to indecency if you don't fully understand the criteria. A court may then make the wrong decision because they rely too much on the police for initial guidance of an offence.
It is a myth that the law in the UK a gives the right to be naked whenever wherever one pleases. The Scotland Yard guidance clearly states that it must be expressed in a way that does not cause offense or distress of any kind. So police are well within the law to investigate a circumstance where someone reports offense or distress. That is why a British Naturism advises group activity instead of solo rambling naked in general public.