This is an old revision of the document!
This might at first seem like a silly question. You attended the police station and you made some notes. Who owns them must be obvious. Think again!
The notes you make at a police station are not yours. They belong to the client. You acted on behalf of a firm. They instructed you on behalf of a client. The client owns the notes.
Many police station reps keep copies of the notes or keep the originals. Do not be tempted to keep any client documents. They are not yours. They belong to the client. You made notes at the police station but they are not yours.
Moreover you do not want the notes. Imagine the police raid you and grab them all and then argue that privilege does not apply, its not likely but who needs that grief? More seriously imagine you are holding notes on a sexual offence. There are rules on how those should be stored and its a pain: keys, log books, special secure cabinets.
There is a Law Society practice note on this issue here: https://www.lawsociety.org.uk/support-services/advice/practice-notes/who-owns-the-file/