There is an accepted order of precedence for the hundred plus livery companies within the City of London. These were based on the economic or political importance of the various companies in the sixteenth century. The top five in order of precedence are Mercers (General Merchants), Grocers, Drapers, Fishmongers and Goldsmiths.
Numbers six and seven have been in dispute by since both the Merchant Taylors and the Skinners companies were incorporated under royal charter in 1327.
The phrase ‘on sixes and sevens’ was used by Geoffrey Chaucer in 1374.
In a ruling by in 1515 it was agreed that the companies would alternate the numbers six and seven. The Merchant Taylors are normally sixth in the order of precedence in odd numbered years, and at seven in even numbered years; this exchange takes place each year at Easter and members of each company dine in each others halls.