Mobile phones and tablets contain a lot of information about your personal life that you probably don’t want the police reading.
Police do not have powers to read through or look at images on your phone unless searching you under the Terrorism Act. The most effective way to prevent casual viewing is by using some form of pin lock.
Regardless of what power they are using, they can not demand that you delete any photos from a phone or digital camera.
After an arrest, the police can download information from your mobile phone into their computers. Most operating systems such as Android and iOS have the option of encrypting your device and messaging systems in order to protect your data.