Miranda Richardson accepted the Dilys Powell Award for Excellence in Film at the London Critics' Circle Awards.
The Mapp And Lucia star was honoured at an intimate ceremony at The May Fair Hotel, hosted by Sightseers stars Alice Lowe and Steve Oram.
Richardson was presented with the award by The Hunger Games star Stanley Tucci.
She said of receiving the honour from the critics: "Well, they're a hard bunch to please and you can't please them all the time, so it's very nice. On balance I'm winning!
"It feels very nice indeed. It is for body of work it's not for one particular role, and that's always nice to think that people have noticed work over time. So even if you don't feel that that's happening, somebody's taking note."
Richardson, 56, is perhaps best known for her role as Queenie in hit BBC sitcom Blackadder, but has enjoyed a long and successful career on the silver screen.
She has twice been nominated for an Oscar, for her portrayal of the poet TS Eliot's first wife Vivienne Haigh-Wood Eliot in Tom And Viv in 1994 and for her performance in Louis Malle's Damage in 1992. The latter also won her a Bafta for Best Suporting Actress.
Richardson has also won two Golden Globe awards, for 1992's Enchanted April and 1994 TV film Fatherland.
Her other big screen roles include Harry Potter And The Goblet Of Fire, Made In Dagenham, Empire Of The Sun, The Crying Game, and Sleepy Hollow.
She is currently appearing in Testament Of Youth, the movie adaptation of Vera Brittain's memoir of the First World War, in which she plays Brittain's Oxford university tutor Miss Lorimer.
Tucci said of Richardson: "Let's face it, she's one of the greatest actresses ever. Her versatility is extraordinary - in comedy, in drama and she's been doing this for a long time now."
He added of her roles: "They're all my favourites, but Blackadder is one of my favourites."
Boyhood was the big winner of the evening scooping three awards, including Film Of The Year, Best Director for Richard Linklater and Best Supporting Actress for Patricia Arquette.
Linklater's 12-year project, which chronicles the growing years of Mason Evans Jr, played by Ellar Coltrane, has already collected a number of awards, including three Golden Globes, and is tipped for Oscar glory.
Linklater admitted getting an award from movie critics meant something special to him.
He said: "To me it's the top of the top because they're people who know film history and they see every film. So as much as I'm touched by someone on the street saying, 'I saw your film and here's what it means to me,' that's great, but this another level.
"Not to be elitist, but in this world of film, those writers are important because they know quite a bit about what they're talking about, so you take it more seriously, and it's that much more of an honour."
He said of Boyhood's phenomenal awards success so far: "A bit of it feels like a roulette game, just luck of the draw, you have no control over it so, it feels like a big bonus when it happens. Happy for everybody who worked on the film. It's exciting for everybody."
Actor of the Year went to Michael Keaton for his portrayal of a fallen Hollywood star trying to revive his career in Birdman, while Julianne Moore was named Actress of the Year for her moving performance as a professor diagnosed with early onset Alzheimer's disease in Still Alice.
Rosmund Pike was awarded British Actress of the Year for her work in David Fincher's thriller Gone Girl and her part in British comedy What We Did On Our Holiday.
Timothy Spall was on hand to collect the British Actor of the Year award for playing the artist JMW Turner in Mike Leigh's Mr Turner.
He admitted his relationship with the critics fluctuated, but winning the award felt good.
Spall said: "I read 'em (reviews), not all of 'em, sometimes I don't. You think they're a really lovely, great bunch of people when they're giving nice reviews, and you think they're horrible when they don't. And sometimes they're right, sometimes they're wrong, but you need 'em really.
"They're people who spend their living looking at films, so when you get nominations at their In house awards, because they're experts - some people might disagree but they are, they do that for a living - it's nice."
Jonathan Glazer's Under The Skin, starring Scarlett Johansson won British Film of the Year and Technical Achievement for its score.