BTW, the news story vanished almost completely due to the other guy who was picked up with knives next to Parliament yesterday, and the woman who was shot by counter-terrorism police last night, but the security services were able to read the Whatsapp message he sent before he attacked, using a mix of "technical" and "human" intelligence (ie; they traced who the message was sent to, and threatened to break their fingers unless they unlocked the phone and let them read it).
The message itself was the usual jihadist nonsense, but it shows Amber Rudd's bizarre desire to install a government backdoor in every device in the country to circumvent encryption for the tedious nonsense it is.