sorry my bad i tought i heard that from somewhere. this was the reason
To help finance his war to conquer Wales, Edward I taxed the Jewish moneylenders. However, the cost of Edward's ambitions soon drained the money-lenders dry. When the Jews could no longer pay, the state accused them of disloyalty. Already restricted to a limited number of occupations, Edward furthermore abolished their right to lend money at interest with the Statute of Jewry, 1275, [1] and eventually restricted their extra-curricular movements and activities. This Statute also decreed ..."that each Jew after he shall be seven years old, shall wear a badge on his outer garmet that is to say in the form of two tablets joined of yellow fait {felt} of the length of six inches and the breadth of three inches."
In the course of King Edward's persecution of the Jews, he arrested all the heads of Jewish households. The authorities took over 300 of them to the Tower of London and executed them, while killing others in their homes. Finally, in 1290, the King banished all Jews from the country, by the Edict of Expulsion.