The BBC drama, which has been brought to the screens by Line of Duty creator Jed Mercurio, has gripped audiences for the last few weeks.
And it all came to a culmination in a tense, blood-soaked finale last night.
Viewers finally found out who killed Home Secretary Julia Montague, played by Keeley Hawes.
But no one predicted it to be David Budd’s (Richard Madden) own boss Chief Superintendent Lorraine Craddock (Pippa Haywood) – helped by mob boss Luke Aitkens (Matt Stokoe).
And in a final twist in the six-episode show that has been filled with high octane conflicts, suicide bomber Nadia (Anjli Mohindra) was revealed to have built the bomb that killed Julia.
But Chris, who served in the SAS for 10 years before running bodyguard teams, has identified one aspect of the show that is very wrong.
Speaking exclusively to Daily Star Online, Chris said: “Whenever you see the Prime Minister or any high-ranking official, they would also have a female bodyguard.
“The simple fact is you would have a mixture of men and women but the close bodyguard to [Theresa May] would be a female.
“You can’t have a guy standing outside the washrooms waiting for her to come out, so that didn’t add up”
“When she goes into a restaurant or any facilities if she needs to go to the bathroom, that WPC [Woman Police Constable] or bodyguard would have to go in there and check it.
“You can’t have a guy standing outside the washrooms waiting for her to come out, so that didn’t add up.
“But you’ve got to have a love interest and the rest of it.”
Chris also said that the whole series is a “million miles away from the truth” of personal protection for government officials.
The Daily Star went behind the scenes of the studio which provided special effects for the show earlier in the series.
Chris was speaking to Daily Star Online to promote his new fiction book “Head Hunters”, part of the Danny Black series.
He served in the SAS for 10 years, fighting in the Gulf War and making the longest escape and evasion mission in SAS history for which he was awarded the Military Medal.
“Head Hunters” is available to buy now. You can follow Chris on Instagram @exsaschrisryan