Changes under Edward I
Edward I made the meeting of Parliament a more frequent event and over the course of his reign of 35 years (1272-1307) he summoned it on 46 occasions. For the first 20 years of his reign it met regularly - almost twice a year. From 1278 official records were kept of its proceedings and decisions, written up and sewn together in long scrolls, the Rolls of Parliament.
Edward 1's first Parliament
In 1275 Edward I called his first Parliament. He summoned nobles and churchmen, but also issued orders (known as writs) for the election of two representatives from each county (the knights of the shire) and two from each city or town (the burgesses) to attend.
They were called on primarily to listen to and approve the King's plan for a new tax. Over the following years it became an accepted rule that the representatives of those who were going to be most affected by taxation had to give their consent to it in Parliament.
Model Parliament
However, the practice of summoning these representatives did not become standard for many years. The next time the burgesses were summoned along with the knights of the shire was in 1295. This was to become known as the Model Parliament, because its representation of two knights from each county and two burgesses from each town became normal for (almost) all future Parliaments.
Parliament and taxation
Parliament developed in the 13th and 14th centuries largely through the desire of Edward I and his successors to wage war. This needed more money than they had from their own wealth and they had to levy "extraordinary" taxes, with Parliament's assent, to raise the funds. But each time the King requested assent to a tax from Parliament, it could ask a favour back again and often used the King's desperation for money to get what it wanted.
Representatives of the people
Since January 1327 when Parliament removed Edward I's son, Edward II, from the throne every Parliament has included representatives of the people. The pattern was now set for Parliament always to comprise three bodies: Lords, Commons and the Monarch.