* I am most grateful to Professor Paul Brand for reading an earlier draft of this
paper, and for making a number of valuable comments on it. I am also grateful to Paul
and Susanne Brand for giving me the use of transcripts made for their forthcoming
edition of
Plea Rolls of the Exchequer of the Jews, vol. vii, hereafter (B). I am obliged, too, to two anonymous referees for valuable
suggestions to improve this article.