A Vexilation fort was built here in the Neronian period. This is one of about twenty-five forts that were established at the time of, or after the conquest but before the Boudican revolt. It was replaced in the Trajanic/Hadrianic by a smaller fort.
http://roman-britain.co.uk/places/letocetum.htm
http://en.wikipedia.org/wiki/Letocetum
http://www2.rgzm.de/transformation/unitedkingdom/smalltowns/Img14.htm