Complex sentence: Probably the longest standing community television service in the UK is Swindon Viewpoint which is over 40 years old and operates according to the core community TV principles of access and accountability-it's Board is elected by its public.
Split into simpler sentences: Probably the longest standing community television service in the UK is Swindon Viewpoint, which is over 40 years old. It claims to operate according to the "core community TV principles of access and accountability", and its board is elected by its public.