Metropolitan Police:

Count 3: Preparation for terrorism. Between 31 December 2015 and 22 September 2016 Samata Ullah, with the intention of assisting another or others to commit acts of terrorism, engaged in conduct in preparation for giving effect to his intention namely, by researching an encryption programme, developing an encrypted version of his blog site and publishing the instructions around the use of programme on his blog site. Contrary to section 5 Terrorism Act 2006.

I can understand the other charges, but how is using HTTPS a criminal offence?

Rick Falkvinge has a few interesting comments on the subject:

(…) four years ago, I predicted that the UK won’t just jail you for encryption, but for carrying astronomical noise, too. It’s already a crime to not give up keys to an encrypted document in the UK (effectively making encryption illegal), but it’s worse than that – it’s a five-years-in-prison offense to not give up the keys to something that appears encrypted to law enforcement, but may not actually be. In other words, carrying astronomical noise is a jailable offense, because it is indistinguishable from something encrypted, unless you can pull the documents the police claim are hidden in the radio noise from a magic hat. This case takes the UK significantly closer to such a reality, with charging a person for terrorism (!) merely for following privacy best practices.