Ah, Patum Peperium - The Gentleman's Relish. Rather decidedly English, I think. How to describe to the uninitiated? Well, it is basically anchovy butter.
It was created in 1828 by an Englishman called John Osborn. It tastes very strong, very salty and slightly fishy and contains anchovies (minimum 60%), butter, herbs and spices. The exact recipe however has remained a secret and was passed down by word of mouth over the years. Today, only Elsenham Quality Foods in Elsenham, England is licensed to make it.
The traditional way of eating Gentleman's Relish is on thin slices of buttered white bread toast, either on its own, or with cucumber, or mustard and cress.
-- from the Wikipedia
If Marmite is "you either love it or you hate it", then Patum Peperium is Marmite on 'roids.
Found some rye bread slices in the freezer from a loaf I bought at Harrod's a while back. So, toasted them up and had with lashings of Patum Peperium and coffee. Then had two fat figs from the market; 4 for £1.00 and gorgeous they were, too.