The earliest runic inscription known in England was found in a cremation cemetery at the former Roman town of Caistor-by-Norwich, Norfolk (the name comes from Latin castra, 'fort'). It is written on a roe-deer's ankle-bone (astragalus), which was probably used as a plaything (perhaps a die in a game), and reads raihan, 'roe-deer'. The runic scholar R I Page draws attention to the shape of the H rune, which has a single cross-bar: this was typical of northern runic writing, rather than the system used further south in Frisia (where the H was written with two cross-bars). It suggests that the person who used this script came from Scandinavia, possibly southern Denmark. The significance of the find is that it dates from c.400. This person was living in East Anglia well before the Anglo-Saxon invasions began.
[See page 9 of The Encyclopedia: EARLY INSCRIPTIONS]