I am a member of a parish council and recently discovered that sometimes the minutes of a meeting are written up by someone else and changed. Is this ethical?? Can/should this be done? :

No, it shouldn't be done if the record of the meeting is distorted. If someone keeps notes and someone else (hopefully someone who was at the meeting) prepares the minutes from the notes it is probably OK. Minutes are usually distributed and approved at the next meeting so members of the committee have an opportunity to object and do in my experience.