The American way of using fork and knife is inefficient and inelegant.

If you really want efficiency, eat South-East Asian style: spoon in the right, fork in the left. The fork is used to hold onto larger things and to rake food onto your spoon, but it never goes into your mouth; the spoon shovels food into your mouth, and its edge can be used to cut as well. This way you can plow through rice and curry like you wouldn't believe, and it's a surprisingly good way of eating even things like chicken legs doused in sauce without getting your hands dirty.

In much of Asia, knifes are reserved for the kitchen, where it's the cook's job to chop everything up into bite-size pieces before being served.

God I hate it when people try to push this stupid line...

I used to live with a British flatmate who was otherwise a nice person, but would constantly harp on me when I was eating "You're using your knife and fork incorrectly."

So for a while, I tried it her way, just to see if I could get used to it, and if it was actually better. After a while, I could kinda do it, but frankly, it always felt awkward and clumsy, and there was no obvious advantage.

Both techniques have their merits—lack of switching -versus- use of primary hand for extra knife power/control—but frankly, both work just fine, neither is obviously superior, and the main difference is what you're used to (in most cases, over decades).

If you're eating dinner the the Queen, then yeah, take a cutlery course first, learn how she does it, and try to do that. She probably doesn't care, but hey, you're eating with the Queen, so a little deference to tradition and pomp seems the way to go.

Otherwise, just do what feels natural to you. If someone whines at you, ask them which hand they'd prefer to be stabbed by, and if you're doing it wrong...