It says a lot about Philip French that after 50 years as the Observer's film critic – five decades in which he has watched more than 2,500 movies, written six books on the subject and received an OBE for his services to film – he is nervous enough about this interview to have researched his answers in advance.

When I arrive at his house in Tufnell Park, north London, I find French poring over a thick reference book at the kitchen table. A cup of coffee is left to cool as he thumbs through the relevant footnotes, anxious to get the facts absolutely right. He will turn 80 in a couple of weeks and says that he occasionally struggles to remember names of directors or actors.

All of this is rubbish, of course, because as soon as we start to speak, French displays an extraordinary recall of fascinating movie trivia. Almost every film he mentions is accompanied with a date of release. He peppers his conversation with anecdotes about meeting Graham Greene and Jorge Luis Borges. In fact, French talks as he writes – eloquently, with absolute mastery of his subject and a startling degree of insight. Listening to him is a pleasure as well as an education.

The scope of French's experience and knowledge combined with the clarity of his writing have made him one of the pre-eminent film critics of modern times. It's no surprise, then, that when he announced that he would be stepping down at the end of this month, there was a collective sigh of dismay from both readers and film industry figures, many of whom later contacted us with questions they wanted to ask him before he retired. Below is a small selection of them. French's answers are as illuminating, informative and funny as his reviews.

You wish he could go on for ever, but as French himself says: "I think one of the key rules to learn in the art of party-going is when to leave with dignity."

It's sad to see him go. But for 50 years there is no doubt he has been a terrific party guest.

Philip French answers your questions

Marlon Brando and Maria Schneider in Bertolucci's Last Tango in Paris (1972). Photograph: Allstar

In your recent review of the revival of Heaven's Gate you write that you and a couple of other major critics were among the film's only supporters on its original release. Have there been other cases of reviled films that you were a rare supporter of? And have you ever championed a film, only to change your mind years later?

Andrew Eaton, film producer

I was a considerable champion in the early 1970s of Bernardo Bertolucci's Last Tango in Paris. I was championing it against the demand that it should be banned and, indeed, Lord Longford attacked me on the radio for having supported it. I still think it's a film of some significance but I no longer think it's a towering masterpiece and much of it now strikes me as downright bad, not to say embarrassing. It remains a milestone but it wasn't the masterpiece I claimed it to be then.

Did you ever write a negative review that the actor, writer or director read and argued with you about? If so, did you feel guilty?

Eoin O'Faolain, Dublin

I did write a piece that I did regret. I wrote an unfavourable review of International Velvet by Brian Forbes and I made a joke about his taste and his family's views… He was hurt by it. I subsequently wrote a sort of apology to him and we became as friendly as one can get with a film-maker. It's not easy for a critic to remain friendly with movie-makers. I've been friends with a great many playwrights and novelists but not with any directors.

[Elizabeth Day] That might change now you're retiring…

I get on well with a great many of them and they've been generously disposed towards me. As I've been doing it for so long, I think people have come to realise that anything that I write about them or anyone else involved in movies comes from my passion for film and not from any desire to promote myself personally or to score easy points. I'm quite prepared to score expensive points [laughs].

Mike Leigh. Photograph: Sarah Lee for the Guardian

Have the conditions for the cinema of the independent, individual voice got better or worse, and when were they best?

Mike Leigh, director

I think there's always been a problem within the film industry for independent and individual voices. Probably the best time for them was one of the great ages of British cinema which was the 1940s, both during and after the war. Nowadays, probably the only significant films being made in this country by British film-makers with a local audience in mind are the independent and individual people like yourself, Terence Davies, Peter Greenaway and, of course, Ken Loach. It is the films they make that justify the existence of cinema in this country and it is very brave of them to stay in this country and make such films.

Orson Welles in Citizen Kane.

What is the best film you've never seen?

Steve Corbett, London

For a long time the best film I'd never seen was Citizen Kane. It opened in the Liverpool suburb where I grew up and closed after three days. My father [an insurance salesman] thought it was a wonderful movie and, indeed, was well known as the only person in his particular peer group who had understood the movie. It wasn't until I was 21 that I saw it. I was in my first year at Oxford University [French served in the Parachute Regiment between the ages of 18 and 21 and so delayed taking up his place to read law at Exeter College] and the arts cinema started each term showing Citizen Kane. I was absolutely not disappointed. When I saw it I'd been looking forward to it for about 14 years.

What is your guilty movie pleasure? There must be something that you know is absolute tripe but you enjoy anyway.

Iain Collett Wychnor, Staffs

Going to the movies became, for a while, a guilty pleasure in itself… My parents believed that work, if you enjoyed it too much, couldn't be work: it was something you did to earn your bread with the sweat of your brow. It was partly to relieve this idea that I turned what had been pleasure into work – in the same way, probably, that some snooker players become professionals to make up for their misspent childhood. If one were to dredge up something to make one feel guilty, it would be that I now find The Sound of Music enjoyable.

Joanna Hogg. Photograph: Felix Clay

Which film-maker of your generation do you feel has spoken most clearly to you? Who has reflected in their films your life changes and your interests?

Joanna Hogg, director and screenwriter

If by "my generation" it would be people whose careers as film-makers occurred through my lifetime, that would encompass, I suppose, Ingmar Bergman, Satyajit Ray, Akira Kurosawa. They are people whose films have greatly influenced me – the way I've thought about life, about the human condition and about the spiritual life, about politics. I've found the film-makers of the New Wave [influential] – politically: Godard for a while, emotionally: Truffaut for a long time. But also, coming after them, Bertrand Tavernier is a film-maker with whom I feel a considerable intellectual affinity because of his literary and aesthetic tastes.

Of film-makers in Britain I would say certainly Mike Leigh… but he perhaps came too late in my life – I was an old dog by the time he started making films and not in a position to learn new tricks.

Michael Powell, although he's not exactly my generation, had an immense influence on the way I saw society and the nature of Englishness. For a long time I saw little real merit in English films, which seemed to me too narrowly middle-class in their tastes and subject matter. Powell's films – starting in the mid-40s, by which time I was 15, 16 – made me think of being English in a rather special and magical way. Another person I grew up with who is almost exactly my age is John Boorman. In some cases he has made films I would have liked to make had I been a film-maker.

Ida Lupino. Photograph: Allstar

[ED] It's interesting that there are no women on that list…

I grew up seeing women on the screen, seeing films written by women, edited by women. I saw hardly any films at all that were directed by women. There were hardly any women who were film directors at all in this country until the past few years. In America there was one in the 1940s – Ida Lupino – who made rather good, often provocative low-budget movies about bigamy, social snobbery, ambition, the state of women, and she, interestingly, was born in this country and was lured to Hollywood as a young woman, where she was an established actor before she started directing. One of the big things that has happened in this country in the last few years has been the emergence of gifted women directors with real feelings for the movies – Lynne Ramsay especially but not alone.

Ken Loach. Photograph: David Levene

Why are you retiring so early?

Ken Loach, director

That is a rather charming question. I made up my mind some time ago that I would retire either on the week of the 50th anniversary of my first film column for the Observer which was in 1963 or on my 80th birthday. We opted for the latter which is why I'm going at the end of August.

Where do you like to sit in the cinema?

Dawn Lindsay, London

Nowadays I tend to sit near the front but not too near. When I grew up, the cheap seats were at the front. When I was young it was a special treat to sit in the posh place in the circle – those seats were for a "better class of person".

Is cinema getting better or worse?

Steven Hughes, Bristol

Some things are better; some things are worse. It's become, in my life, a very different experience. It [cinema-going] is only for a few people a habit, a major part of their life. During most of my life the only way you could see a film was by going to the cinema. I didn't even own or rent a television until my early 30s. British cinema has been in a permanent state of crisis since it became something approaching an industry in the 1920s. There have been great periods – for instance, during and after the second world war when cinema found a great patriotic purpose and had a major role in society that was recognised – but it has been very difficult since then to make a career in British cinema. You had to fight your way film by film.

Every cinema has had its golden age. It often took very little to destroy. Swedish cinema, for example, was a world leader during the time of the great war. It just took Hollywood to hire the two greatest directors [Victor Sjöström and Mauritz Stiller] to kill Swedish cinema. In the 1920s, German cinema had one of the great golden ages of, I think, western art. As most of the people connected with it were Jewish, the coming of Hitler brought it to an end. The only people who remained were people prepared to go along with the Nazi party. They were hacks of some kind. The others went abroad – some to this country, most to the United States.

[ED] And then of course you had the McCarthyite anti-communist period in America. Do you think that had a similarly damaging impact on the movie industry?

That is an interesting question because one of the significant contributions made to British cinema was the House of Un-American Activities Committee of the 1940s and 50s where people, rather than inform on the politics of their friends, either took the Fifth Amendment or refused to work under those conditions, and many left to work in the UK. Some of them created new careers, particularly Carl Foreman or Joseph Losey.

Losey was somebody who I championed when I was first a critic. In 1963, in one of my first columns for the Observer, I went to see The Damned, a Hammer movie made by Joseph Losey. It was released without a West End screening and opened in a suburban cinema. I went to see this film and devoted most of the column to an enthusiastic review of the movie and Losey's significance.

It helped make my name. People went to see it and it was reviewed elsewhere, and United Artists, encouraged by these reviews, brought it into the West End. I got a letter suddenly from Joseph Losey. I'd never met him. First of all I thought it was a practical joke but it was a genuine letter. "Thank you," he said, "for praising it and not for overpraising it." And he went on to say: "This has changed the situation for myself and my associates."

Dirk Bogarde and James Fox in The Servant. Photograph: Rex Features

I didn't quite understand what he meant by that until I discovered some weeks later that he had made a film on a small budget with everybody deferring their payments, a film called The Servant which is one of the finest films ever made in this country. And what he was saying was that my review had prepared people for it – he'd never made a film in Britain that had much appealed to British critics.

Have you ever been offered sex or drugs to alter a review? Or both?

jantomrukthefirst, posted online

Unfortunately, no. I think I took a cigarette from a film-maker once at a party.

Garbo in The Divine Woman.

As you are probably aware, many films from the 1910s, 20s and a few from the 1930s are classed as "lost" – ie no copy is known to exist. Is there a particular lost title you wish you could see and, if so, which one and why?

Norman Fay, High Spen, Gateshead

Yes, there are a number of movies I would love to see rediscovered, one of which is the film The Divine Woman, which was one of the silent movies of Greta Garbo, directed by Victor Sjöström, the man who before Ingmar Bergman was the greatest Swedish film director and who went on to play the professor in Bergman's Wild Strawberries. The one I would like to see properly restored is the 1933 film The Power and the Glory, scripted by Preston Sturges, who became one of my favourite directors. It is the film that really provided the formal blueprint for Citizen Kane. I would also love to see Orson Welles's The Magnificent Ambersons restored. RKO cut something like 30 or 40 minutes out of the film and it's never been seen. No one's ever found the footage.

Is there still a role for the print film critic in the digital era?

Tom Beasley

Yes. I don't think that any critic in any medium will have the same influence that certain critics have had in the past. I am not anything like as influential as my longest-serving predecessors Caroline Lejeune or Dilys Powell but I think there will always be a place for good critics. I'm sure there will also be plenty of indifferent critics employed because they are personalities of kinds and write in an entertaining way but I don't think that criticism will ever have influence in the same way again. Indeed, many newspapers in America now think they can get along perfectly well without them. But of course, most of them manage to get along without decent writing too.

Paul Newman in Hombre. Photograph: Allstar

[ED] Did you take your three sons, Sean, Patrick and Karl, to the cinema when they were little?

All my sons love movies. I started taking them around the age of four. I would take them to films I thought were quality, so I made sure that by the age of five or six they had seen the complete works of the Marx Brothers. They often tease me about when I took them to see a double bill of two westerns – Hombre and Butch Cassidy and the Sundance Kid – and quizzing them afterwards to make sure that they had been convinced that Hombre was a much better film than Butch Cassidy!

What is your opinion on leaving films before they've finished?

Chris Saltmarsh

This often comes up and the answer to this is that I have never done so. I always ensure I'm there before the lights go down and I always remain to the end of the credits. I'm amazed that people's lives are so busy they have to get up and rush off before the credits end. Often there's so much information to be had about where the film was made. Most films now have 30-second bits on something that reflects in an ironic or oblique way on the film you've just seen. For instance, at the end of [the newly released] The Lone Ranger, which is an underrated film I think, there's a lovely shot of Johnny Depp as Tonto as an old man looking out over Monument Valley. It's very touching. People miss something by not staying to the end. The only occasion I might have not done so was when I was in the army, from 1953 to 1954, and I had to catch a train or go back to barracks.

[ED] Where do you keep your OBE?

This is embarrassing. I actually keep it in a drawer upstairs.

Do you see any directors on the horizon who could become giants of cinema?

Valentine Montagnani, London

A director I supported just a few years ago was Christopher Nolan. I saw his first film at the Dinard film festival. It was made on a shoestring and was called The Following. I thought it was one of the best recent British films and I did predict he was going to be a major director. He went on to make Memento and I wrote an unreservedly positive review about it. He both fulfilled his promise by becoming one of the major film directors, and he's also, unfortunately, got too involved in expensive movies. I would like to see him make a few more modest films, like Memento, which didn't have a £25m special-effects budget. Of his most recent films the one I thought was the best was The Prestige.

[ED] What about actors: do you see any of the current crop having the same lasting impact as Brando or De Niro?

Ryan Gosling has a presence with which he can command a film. I think Only God Forgives you could say is a Ryan Gosling film – he really is what holds your attention.

I think Matt Damon is a wonderful actor. If you look at him he looks like someone who has just been signed up for a team of Irish-American builders and yet he has an extraordinary charisma and also, he hasn't got the mannerisms of a star: he's an actor without ego.

The other person who has gone from being a juvenile to a serious actor is Leonardo DiCaprio, particularly in the films in which he's collaborated with Martin Scorsese. He was remarkable in The Departed and his performance as Howard Hughes in The Aviator is uncannily accurate. I would say both of them [Matt Damon and Leonardo DiCaprio] are actors in a class of the very brilliant but mannered and somewhat self-regarding Anthony Hopkins.

Do you eat popcorn when you go to see a movie?

origamiskyscraper

I have never eaten popcorn in a movie house or anywhere else for many years. I've never cared for it. One of the benefits of having diabetes is not to be tempted to eat popcorn. I don't like the smell of it. I don't like the sound of it.

One of the greatest disappointments of my life was drinking my first Coca-Cola after the second world war. It was not the drink of the gods and, indeed, is not to be drunk in the gods.

You've often treated us in your reviews to the odd good/bad pun. What was your favourite?

Misterlks

I do like making puns. A lot of people with speech impediments [French has a lifelong stammer] find themselves making puns, because if you get words and letters mixed up in your head you can make a joke of it.

Back in 1978, in my very first column that I wrote as the full-time Observer critic, my main review was of the film 1900 by Bertolucci. My predecessor, Russell Davies, had done a review the previous week of Steven Spielberg's Close Encounters of the Third Kind. There was a scene in 1900 in which an Italian fascist played by Donald Sutherland is pelted with horse shit by communist peasants, and I referred to this as "a close encounter of the turd kind". Then, a few years ago, I was asked by the Observer to write about a series of new British stamps which featured movie stars… I began the piece by saying: "I don't know much about philately but I know what I lick."

What is the ideal length of a film?

Lightlight

There is no ideal length. Heimat lasts for 12 hours and needs to be seen over several days. Battleship Potemkin lasts an hour. You can be bored to tears by a six-minute cartoon. Edward Albee put it best when someone talked about Who's Afraid of Virginia Woolf? being his first full-length play. He said: "All my plays are full-length. They're full to their length."

Which critic do you most enjoy reading?

FreakyChucker1

It's difficult to talk about your contemporaries, it's invidious. There are certain critics that I just love to read for the pleasure of their thinking and writing. Hazlitt is a great favourite of mine. More recently, the critics who have influenced me are Edmund Wilson, whether writing about literature, poetry or theatre – he's probably the greatest general reviewer of my lifetime. Lionel Trilling I admire greatly. In America, James Agee. And Graham Greene of course – I have enormous regard for everything he wrote, and just by talking about films he illuminated the medium and the art and he was marvellously un-snobbish about popular culture. There were no sacred cows for him.

Have you ever written a film script or attempted to make your own film?

Saiqa Khan, London

Yes. During my first year at Oxford I was involved in writing and post-production for a satire on Oxford life called Folly Bridge. It was useful to list on my CV. The director of the film and the producer both got scholarships to film school as a result.

Philip French with his wife, Kersti. Photograph: John Reardon

[ED] Do you and your wife, Kersti, share the same taste in movies?

Mostly we tend to agree. Our paths first crossed in a cinema without us realising it. In 1957, I got a scholarship to the University of Indiana journalism school. I had a week in New York before going out to Indiana and, as everybody did in those days, I went to Radio City Music Hall, and the movie playing was The Pajama Game, which had one of my favourite stars in it – Doris Day. I have a very soft spot for her. About three weeks later I met Kersti, who had come from Sweden on a scholarship to study English literature there. We were in the same residents' block for graduate students.

It turned out that her boat had arrived on the same day as mine and she had gone to Radio City on the same day and we had both gone to the same viewing. Both of us had travelled some 700 miles, converged on New York on the same day, and both of us were heading out halfway across America to the midwest. At the end of that year, on New Year's Eve, we got married. We'd known each other for three months.

Who was the best Bond?

Colin Cooper, Westcliff-on-Sea, Essex

Sean Connery, without doubt. And my favourite Bond movie, because it was the first, is Dr No. On the other hand, I have a very soft spot – my body is covered in soft spots – for George Lazenby who I thought was unfairly abused. On Her Majesty's Secret Service [in which Lazenby plays 007] is one of the best Bond movies.

How do you cleanse the palate after watching a soul-destroyingly crap movie?

Chris Browne, Chilwell, Notts

I suppose the way, without resorting to alcohol, is to see a favourite movie. After seeing one of the Hangover films or any of the three or four British movies about appalling behaviour at weddings which are quite as bad, I would probably go to the nearest shop and buy a DVD of Annie Hall or Hannah and Her Sisters. That would cleanse any palate.

[ED] Do you have a film that you enjoy purely because it makes you laugh?

Errr… [Kersti shouts from the hallway: "Bringing Up Baby!"]

Yes, Bringing Up Baby, which I see again and again. Buster Keaton's The General. Early Chaplin – particularly the Chaplin shorts The Rink and The Cure – and my favourite of the full-lengths is Gold Rush.

[ED] Didn't you meet Chaplin once?

Yes, in the sense that we were in a group of people at a party for the launch of the illustrated version of his autobiography at the Mayfair theatre in the late 60s. Chaplin must have been about 80 and his face was impassive and frozen. He stood there, a bit too frail or unwilling to shake our hands.

They showed The Tramp from 1916 and he sat immediately in front of me, and I had this extraordinary experience of looking at Chaplin in half-profile looking at Charlie Chaplin at the age of 20, around the point he was becoming most famous. He did not bat an eyelid or give any kind of response to it at all. It was as if it was the Sphinx in front of me and I was looking at the Pyramids. It was very strange.

Which eight reels would you take to your desert island and why?

Christopher Wright, London

It changes all the time, but I would definitely take Singin' in the Rain, Stagecoach by John Ford, either Hitchcock's North by Northwest or The Lady Vanishes, Ingmar Bergman's Wild Strawberries, and at least one of Satyajit Ray's Apu Trilogy – he's one of my great heroes, Ray, and one of the most impressive directors or men that I've ever met. Is that eight?

[ED] No, only five…

Salvatore Giuliano, which is a Marxist movie about Italian politics [directed by Francesco Rosi in 1962]. A Billy Wilder film, either Double Indemnity or Some Like It Hot – I roar with laughter every time I watch Some Like It Hot, and the great thing about it is that it wouldn't take much rewriting to make it not a comedy at all. It really has the courage of its own bad taste and its aesthetic conventions.

And for my eighth I'd take Jean Renoir's La Règle du jeu.

• To mark Philip French's 50 years as a film critic, he will be sharing some of his favourite moments in cinema at the British Film Institute in London on 25 September, in conversation with Sir Christopher Frayling. More details and tickets (price £11) are available from bfi.org.uk or go to theguardian.com/extra for details of how to buy tickets for £9.50