  Isotropic inhomogeneous dust universes are analysed via observational
coordinates based on the past light cones of the observer's galactic worldline.
The field equations are reduced to a single first--order {\sc ode} in
observational variables on the past light cone, completing the observational
integration scheme. This leads naturally to an explicit exact solution which is
locally nearly homogeneous (i.e. {\sc frw}), but at larger redshift develops
inhomogeneity. New observational characterisations of homogeneity ({\sc frw}
universes) are also given.
