He subsequently pioneered ' urban site observation ' and his Illustrations of Roman London ( 1859 ) remained the principal work on the subject until 1909 .
Roach Smith was by this time accepted as the leading authority on Roman London .
Roach Smith subsequently pioneered ' urban site observation ' and Roach Smith 's Illustrations of Roman London ( 1859 ) remained the principal work on the subject until 1909 .
Roach Smith was by this time accepted as the leading authority on Roman London .