This is to be used for defence and critical infrastructure. What is that? I mean, I'm sure there are <£500 phones that tell you where you are based on GPS, Galileo, Glonass and Beidou. The UK will hardly be at war with all of the US, EU, Russia and China.
Feels like a shrewd purchase. Build your own from scratch for 3 billion or take a stake in one already built for 500 million.