British. My mother had a very formal upbringing which she tried to impose on us kids.
Most of what SanVito said, but with a few extras.
You are assigned a napkin which is presented in a napkin ring where you are sitting. For help-yourself style salad meals, you sit and then retrieve your napkin from a pile in the middle of the table.
Fork in left hand, knife in right - and the fork is only ever used for stabbing. It should not be turned scoop-way up. If you have gravy etc. you stab a piece of meat/veg on the fork and use the knife to push the liquids onto the food.
Soup is spooned away not towards, with the bowl tilted away from you. You do not put the soup spoon in your mouth - you rest it on your bottom lip and pour the soup into your mouth.
You do not cut bread rolls, you break them. Butter is put on the side of your side plate using the butter knife and spread a bit at a time onto the bread as required, using your sideplate knife.
Don’t clink the cutlery against your teeth. Don’t scrape cutlery against crockery. Eat with your mouth shut. Don’t talk with food in your mouth. Never put a knife anywhere near your mouth. Elbows off the table. Napkin in your lap. Don’t eat until the most senior woman at the table has started (often, but not always, the hostess). Wait to be offered seconds. Knife and fork together at 12.00 to indicate you are finished. Thank the host/hostess for the great food.
Foreign etiquette I’ve learned:
Chinese - even if there are several foods on the table at the same time, only serve yourself one food into the bowl at any given time, usually onto a bed of rice in the bowl. Bring the bowl to your mouth. Slurp noodle soup. Always rest your chopsticks above the table - edge of the bowl or on a chopstick rest. Never stick chopsticks into anything, and particularly not into rice as this resembles an incense offering to the dead. You can cut with the edge of your spoon. Never touch any food with you fingers.
Thai - spoon in right hand, fork in left. Fork is held tines down as in the British way, but only use the fork for pushing stuff onto the spoon. Don’t ask for chopsticks though occasionally they may be offered for fried noodle dishes. Never touch anything with your left hand.
American - fork in the right hand, scoop-wise, switch hands to cut with the knife. Put the knife down and switch hands again to eat.
Sri Lankan/Indian/Nepalese/Bangladeshi - don’t be disturbed that the hostess isn’t eating with you. Use the right hand only to make little balls of rice/curry, or use a chapati or paratha, torn with the right hand only, to scoop up liquids. Never touch anything with your left hand.
ETA: did any of my mother’s rules persist? Yeah, some of them are completely ingrained and leave me feeling sick if someone, say, licks food off a knife or chews with their mouth open. It’s completely illogical but is so strong I don’t think it will ever leave me. That said, the soup rule and the no-fork-as-scoop rules are completely retarded and I ignore them. And the napkin thing. And it’s fine to eat pizza with your hands in front of the TV. But my mother’s rules have actually served me well in genuinely formal settings, as we all spoke the same unwritten language.