This article argues that the power of the early Mercian kings from
Wulfhere to Aethelbald, c.650-750, rested partly on their ability to
exploit the growing economy which characterised this period; and that
such exploitation provides a hitherto unacknowledged reason for the
rise of Mercia to supremacy. The argument rests on the Mercian rulers'
control of two particular places, London and Droitwich, the first the
country's foremost port, the second a major industrial site concerned
with the production of salt. After the growth of Mercian authority
over both places has been traced, it is suggested that taxation of
their activities may have resulted in substantial profits, via tolls
in both centres and, in Droitwich, via a further levy on the
manufacture of salt. The history of taxation on salt is traced back
from the early modern period in order to see what light later
practices shed upon those of the early middle ages. The article
concludes by suggesting that the Mercian rulers were fortunate in
exercising power at a time when economic growth, partly church-led,
was open to royal exploitation and that those rulers had a conscious
appreciation of the advantages so to be gained.