  We consider the initial value problem (IVP) associated to a fifth order
KdV-BBM type model that describes the propagation of unidirectional water
waves. We prove that the regularity in the initial data propagates in the
solution, in other words no singularities can appear or disappear in the
solution to this model. We also prove the local well-posedness of the IVP in
the space of the analytic functions, the so called Gevrey class. Furthermore,
we discuss the evolution of radius of analyticity in such class by providing
explicit formulas for upper and lower bounds.
