A riveting watch, that begins with a strong presence and which slowly builds on it up to third episode... only to be let down rapidly by shoddy writing. The ending "twist"is cheap, the supposed "culprits"have little motive and much of the previous hints, murmurs, whispers and observations turn out be a massive waste of the viewers. Naturally, critics, being born both blind deaf to good film, don't pick up on any of this.
SPOILERS;
Does it sound plausible that a crime boss would try have the home secretary assinated simply because he didn't like a bill she passed? No. Not only will that not stop the bill from being passed, it would easier to simply bribe a few politicians to shoot the bill down.
So who actually had a motive? Her sucsessors, obviously. What's more, she was rapidly increasing the power of the secret services and rolling back the powers of the police-- A move her next-in -line strongly disagreed with.
The ending almost writes itself. It would be a much better, albeit darker, if the series ended with a foiled coup, including almost all higher ups of police force and senior cabinet ministers. An ending in which the secret service(and mr longcross) are in fact instrumental in saving the day. An ending explaining the many private meetings, both public and secretive, between them and Julia Montague.