The last movie I remember really laughing at was Airplane it was the first time I saw it last summer. The humour is so insanely stupid.
Other than that I can't remember laughing too much during a movie.
I did find the stingray in Finding Nemo hilarious for some reason, near the start when he's spinning saying "where'd ya go?".
I always find Norman Wisdoms movies consistently funny.
I'm not familiar with him, but I see from IMDB that he's a British comic actor. I was going to recommend
Blazing Saddles or
Young Frankenstein as two other movies that I find very funny, but since you mentioned a British comic actor from the middle part of the last century, I feel thast it might be better to mention any number of comedies by Ealing studios. I particularly like the ones with Alec Guinness, (
Kind Hearts and Coronets, Our Man In Havana, etc), but there are some others put out by Ealing that are also great;
Passport To Pimlico, Genevieve, and
Whiskey Galore to name just a few.
BUT....for truly hilarious fare, some of my favorites are the old screwball comedies, many of which star Cary Grant:
His Girl Friday
One of many adaptations of the Hecht/MacArthur play
The Front Page, given masterful treatment by Howard Hawks. Sterling performances by Grant, Rosalind Russell, and especially Ralph Bellamy help to make this one of my favorite comedies.
Bringing Up Baby
Another Hawks delight, with Grant paired up with Katharine Hepburn this time. I dare you to watch this and not laugh.
Arsenic and Old Lace
Insane. Completely insane. Grant and the incomparable Josephine Hull top a superb cast of characters in this comedy about a man who discovers that his two sweet old aunts are helping lonely old men by poisoning them and burying them in the basement.
Geez, sorry....I didn't mean to go on like this, but I hope you and others found this helpful.