The best UK-based chocolates were invented in the 1920s and 30s.
Roald Dhal commented that this period was the chocolate equivalent to the Italian Renaissance.
1920: Flake
1921: Fruit and Nut Dairy Milk
1929: Crunchie
1930: Snickers, Freddo
1932: Mars Bar
1933: Whole Nut Dairy Milk
1935: Aero, Kit Kat, Milky Way
1936: Maltesers, Blue Riband
1937: Smarties, Rolo, Milky Bar
What a time to be alive! (…apart from those two massive wars either side)