These conventions remain part of our constitution. Others have developed since Dicey's time. Indeed, the whole system of cabinet government depends on constitutional conventions.

Gradual evolution

Take the Prime Minister, for example. Britain has had one since the eighteenth century, but not because parliament sat down one afternoon and said so.

Walpole: first among equals

Indeed, it was not until 1917 that a statute first noticed we had such a person, when the official 'now popularly known as Prime Minister' was allowed to live at Chequers.

By the same reckoning the cabinet was first spotted in 1937 when parliament decided its members would receive salaries; likewise the Leader of the Opposition.

The Ministers of the Crown Act 1937 did mention in passing that there were such things as political parties, but it was not until 1969 that MPs came out of the closet and allowed party descriptions to be printed on ballot papers.

Constitutional conventions do not last for ever.

As they have not been created by law they do not need formal repeal: people simply stop observing them.