Brexit should be exploited to overthrow a hated European Union law governing marmalade, a German MEP who is furious at the EU’s legal definition of jam, has said.

The directive “on fruit jams, jellies, marmalades and sweetened chestnut purée" rules that a jam can only be called marmalade if it contains at least 20% citrus fruit.

The 1979 rule supports the UK understanding of marmalade as being made from oranges and lemons.

The rare British victory in Brussels has stuck in the craw of Germans and Austrians ever since. Traditionally, jams made from other fruits, such as plums or strawberries, were called marmalade in those countries.

But under Germany’s Konfitürenverordnung (Jam Regulation), which imposed the EU directive into national law, non-citrus jams must be branded “konfitüre” and not marmalade.