Under Henry III other influential men of the realm, aside from the
barons, who were tenants in chief, began to be summoned to the King's
council. These were called "barons by writ." Later (under Richard
II), barons were created by open letters bearing the royal seal, and
were called "barons by patent."[1]
[1] This is the modern method of raising a subject (e.g. the poet,
Alfred Tennyson) to the peerage. It marks the fact that from the
thirteenth century the ownership of land was no longer considered a
necessary condition of nobility; and that the peerage was gradually
developing into the five degrees, which were completed in 1440, in the
following ascending order: barons, viscounts, earls, marquises, dukes.