To mark King Charles III's coronation, Costa Coffee have been prepping their baristas to provide "proper etiquette". The popular drinks chain enlisted the help of a royal butler to put the team through their paces as part of a new 'Barista Butler School'. Uniforms were complete with traditional white butler gloves before learning about silver service, formal afternoon tea service, and napkin folding should Charles ever stop by for his rumoured favourite toasted lunch choice. It comes after Costa launched its new Coronation Chicken Toastie. It features roast chicken with a blend of coronation spiced bechamel sauce, mango chutney, apricots and sultanas in coronation spiced cheese-topped bread, the new Coronation Chicken Toastie. Sign up for our free Indy100 weekly newsletter Etiquette expert William Hanson has since lent a hand in etiquette after research by Costa revealed that less than half of us (45 percent) hold our fork in the left hand when eating, and over three quarters (77 percent) do not follow the ‘6:30 clock face’ rule when finished. Knife and fork "While cold sandwiches are designed as finger food, it’s perfectly acceptable to use cutlery for toasted morsels (despite etiquette from ancient Rome telling us to never to cut bread!). Spear and cut away to your heart’s content - don’t worry about upsetting our Roman ancestors. They’d relax a bit if they tasted a toastie." Getting handsy "If a knife and fork isn’t your vibe and you want to get tactile with your toastie, using your hands is fine too - especially in more relaxed settings. Clean hands, of course, are infinitely preferable to ones you haven’t sanitised or washed before tucking in." Triangles are better than rectangles "Should you be in charge of cutting your toastie in two, please note that in etiquette land, cutting diagonally to make triangles (rather than rectangles) is hugely preferred - not to mention it looks much more aesthetically pleasing." Napkin on lap "Regardless of how you choose to eat your toastie, please do ensure your lap is covered with a napkin - linen, ideally, but paper napkins are better than nothing, as it is best to have something there to catch any spillages. Regardless of your choice of dining establishment, it’s always correct to have protection in the form of napery. Tucking napkins into collars is fine when you’re 18 months old, but a bit tragic when you’re older." Eat the crusts "Since World War II, it’s been the rule to finish all the food on your plate, rather than leaving a little to show you’re full to bursting. This rule still stands - so don’t think you can get away with leaving the crusts. Eat up!" Finger bowl if using finger food "Hear me out, if you’re eating with your hands, it may be best to have a small cut-glass finger bowl close by so you can gently dab your fingers in cold water to wash away any mess on your fingertips. Add a touch of class to the proceedings, why don’t you?" Finished? "If using cutlery to devour your toastie, place the cutlery in the ‘6:30 position’ if you imagine your plate as a clock face. This is the British signal that you have finished eating - and something The King will always do when dining." Naomi Matthew, Food Innovation Director at Costa Coffee commented: "We know how much the nation loves a toasted sandwich and we’re excited to be taking it to the next level with our Coronation Chicken Toastie. "Our Baristas are the best of the best and are already experts in creating the perfect cup of handcrafted coffee, but we knew we had to take our training to another level in honour of King Charles’ coronation. "We’re thrilled to have been able to have a Royal Butler train our Baristas so we can make our customers feel like Kings and Queens during the exciting coronation period." The Coronation Chicken Toastie will be available until 31 May. Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.