Andy Summers’s review published on Letterboxd:
I've said before on LB that many people don't and cannot understand the situation that existed in Northern Ireland during The Troubles. There have been many movies centered around events across the water, from the good, the bad, and the shameful. Hundreds of years of divided bitterness somehow transfixed into a couple of hours of celluloid. The truth is however that nothing was as it seemed in Northern Ireland. There were divided loyalties inside families, but everything was always boiled down to whether you were Catholic or Protestant, Pro-IRA or Pro-British. It was much more complicated than that, something that '71 touches on rather well.
Young British actor of the moment Jack O'Connell demonstrates his ability once again as a British soldier cut off from his unit and left to survive alone on the streets of Belfast. The film never flinches from unveiling the chaos and treachery that was around every corner. Friend or foe, trustworthy or treacherous, it was hard to decipher who was who even on your own side. As O'Connell's young squaddie tries to stay alive he witnesses the influence of the Military Reaction Force, a covert intelligence agency that was responsible for some deplorable actions between 71 and 73. Hunted by the IRA and the MRF, he just about manages to evade capture due to some friendly Catholics who tend his wounds and give him shelter. It then becomes a question of who will get to him first.
Director Yann Demange has certainly done his homework. Little was known about the MRF, even to people who lived through The Troubles. It was only years later that the collusion between the MRF and loyalist paramilitaries in the murder of Catholics became public, something Demange has fitted into this story rather well. It's dramatic and tension filled film-making with intelligence, showcasing O'Connell's star potential in a psychologically gripping white-knuckle chase movie. Demange has also lined up support acts of the highest quality. Sean Harris is, as always, a force to be reckoned with, but with Paul Anderson and David Wilmot bringing their own level of authenticity to proceedings, this is an impressive debut film for Frenchman Demange. O'Connell is already a star, and I can't wait to see what he does next.