This paper describes a search for the Standard Model Higgs boson
using $\rm e^+e^-$ collision data,
with centre-of-mass energies between 192~GeV and 209~GeV,
collected by the OPAL detector at LEP.
The consistency of the data with the background-only hypothesis
and various Higgs boson mass hypotheses is examined.
A lower bound  is obtained on the Higgs boson
mass at the 95\% confidence level.  At higher masses, the
data are consistent with both the background and the
signal-plus-background hypotheses.