The 70-year-old actress starred opposite the late actor - who tragically passed away in January at the age of 69 - in the drama thriller and she is "incredibly sad" it will be his last film.
Speaking on the red carpet at the UK premiere of 'Eye In The Sky', she said: "It's incredibly sad to have to say goodbye to Alan, not least because he was far too young and he had such great work in him, ahead of him, as you'll see from his performance in this film, which is fantastic.
"The great thing is, it's very much Alan on the screen. It's not him playing one of his amazing characters - it's Alan as we all knew him and remembered him - so it's a lovely way to say goodbye."
Meanwhile, Helen previously revealed she thought Alan would have been "really, really proud" of the movie.
She shared: "The Alan we see on the screen in 'Eye In The Sky' is Alan. It's Alan as I remember him. His wit, his humanity, his intelligence. I think Alan would have been really, really proud for this to have been his last film ... Alan was a genius character actor and he could play all these amazing baddies."
