From the Middle Ages until the Industrial Revolution, Norwich was the largest city in England after London, and one of its most important cities; it's status being based on the wool trade. During King Henry's reign the Great Hospital dates from 1249 and the College of St Mary in the Field from 1250. In 1256, Whitefriars was founded. In 1266 the city was sacked by the "Disinherited". (Wikipedia) 

The Churchill & Thomas 2012 publication on the Brussels Hoard documents 729 Norwich pennies from classes 3a1 to 3c. Amongst the coins present in the Brussels Hoard, Class 3a2 pennies are the rarest for Norwich, with only 5 documented.   As at other provincial mints there were four moneyers appointed, and for Norwich these were Hugo le Brunham, Jacob Cocus, John Martin and William of Hapesburg, the latter being the least common in the Brussels and Colchester hoards. 

A significant number of additional Norwich coins came on the market during June 2017, when Baldwins auctioned a number of coins from their basement vault ... we do not know whether these originated from the Brussels Hoard but it would not be unreasonable to assume that as being likely.  Long cross pennies sold were 46 of the moneyer Hugo, 26 of Iacob, 43 of Ion and 29 of Willem, an overall total of 144 coins.  There were a number of coins in these lots which were either scarce or absent in the 729 coins from the Brussels Hoard studied by Churchill and Thomas, for example a number of class 3c coins of Ion, which were totally absent from the Brussels Hoard study.