From The Independent:
David Cameron is a right-wing reactionary neocon in the same mold as Darth Cheny and Bush II, so this isn’t surprising. At all.
The Prime Minister said today that he would stop the use of methods of communication that cannot be read by the security services even if they have a warrant. But that could include popular chat and social apps that encrypt their data, such as WhatsApp.Apple’s iMessage and FaceTime also encrypt their data, and could fall under the ban along with other encrypted chat apps like Telegram.
This next one, probably meant to be rhetorical, actually has a real answer:
“In our country, do we want to allow a means of communication between people which […] we cannot read?”
Yes, we do.
Update: WhatsApp is bigger than SMS, and iMessage, being huge, might also be.