Not the government, who was never using WhatsApp, the Tory Party.
A Conservative spokesperson said the real justification for their MPs to use Signal was operational, rather than for security reasons. With so many Tory MPs elected at the last election, it had become impossible to fit them all in a single WhatsApp group, because they are currently capped at 256 members.
I wondered if telegram has some feature where you get an alert if someone screenshots the window (I seem to remember snap chat had this?). Do you know?