From the Home Office’s website
“Evidence to put before a court can be a number of different things:
someone speaking directly to the court – a member of the community, yourself, a police officer, a council worker, a warden, a police community support officer, teacher, doctor or a councillor – people who might give evidence to the court of their own experience or of events which have been described to them by witnesses (also known as professional witnesses)
a document which you produce in court to prove the truth of a fact – this can be a written statement or a document such as a tenancy agreement to show contractual obligations
a community impact statement (see article about community impact statements) or
something else which supports the above, such as photographs, a sound or video recording.
The first kind (evidence in person) is almost always best for your case. It allows the judge both to hear the facts and to assess the truthfulness of your witness.”