How long can the police hold you if arrested?

How long can the police hold you if arrested? If arrested the police can hold a person for 36 hours without charge.
The 36 hours starts from the time that the persons arrival at the police station. The detention is reviewed at intervals of 6 hours, 9 hours and 9 hours by an Inspector (up to 24 hours). Then at 24 hours, a Superintendent can extend the custody time for up to a further 12 hours. This extension used to be for serious arrestable offences only, but it is now possible for any indictable offence. This includes such things as ABH, shoplifting, joyriding (aggravated) and possession of drugs.
The Inspectors and Superintendents that review and extend the detention have to be satisfied that the investigation is being conducted diligently and expeditiously and that the detention is necessary. This means that the investigating officers have to demonstrate that they are making enquiries such as taking statements or viewing cctv, as well as interviewing the suspect.
If the police want to hold you for more than 36 hours then they have to apply to a magistrates court for extensions. Extensions may be applied for in blocks of up to 36 hours at a time, up to a maximum of 96 hours from the time that the suspect first arrived at the police station when arrested. So with these warrants of extended detention the police can hold you for a total of 96 hours. The police (not the CPS) make the application to the magistrates for an extension, and although magistrates usually grant the first application, they may not grant as many hours as the police want. This means the police may have to make a second or third application to the magistrates to hold a person for the full 96 hours.
If the suspect attends a hospital for treatment then the custody clock is suspended for the time he is away from the police station. This suspension of the custody clock does not happen if the person receives medical treatment at the police station. When charged with an offence this custody clock stops. Charged means told that you will be prosecuted and given a court date. When charged the police have to either bail you with or without conditions, or keep you at the police station for the next court. None of these times apply to terrorist/terrorism offences.