The first written record of the sandwich was in 1762 and the Kent town of Sandwich, which is the earldom of the Montagu family, is celebrating 250 years of the meal.
The story goes that fourth Earl of Sandwich asked for beef served between slices of bread so that he could eat while continuing to play cards and his friends asked "to have the same as Sandwich", according to the British Sandwich Association.
The fourth Earl of Sandwich was considered "a daring man" to eat with his fingers at that time.
Over the weekend the east Kent town hosts sandwich-making competitions and re-enactments of the moment the fourth Earl of Sandwich asked for the food in bread, the BBC reported.
Sandwich Celebration Festival organiser Mandy Wilkins said it had interest from around the world, including America, Canada, Germany, Switzerland, France and Russia.
"The sandwich is a global food and Sandwich, our town, is just a little town full of medieval buildings. It's bizarre that such an important food item should be named after us," Wilkins said.
Today the 11th Earl of Sandwich, who shares his name with the fourth Earl after which the sandwich is said to be named, hosts a lunch in Sandwich.
John Montagu said: "I am delighted to wish a happy 250th birthday to the sandwich. My ancestor, the 4th Earl, could never have imagined that his simple invention would spawn a multi-billion dollar industry, employing hundreds of thousands of people in this country."
According to the British Sandwich Association the industry employs more than 300,000 people in the UK and has a commercial value of over 6 billion pounds.
"My favourite sandwich is a traditional one: roast beef and hot horseradish on freshly baked bread," Montagu added.