  A strictly linear evolution of the cosmological scale factor is surprisingly
an excellent fit to a host of cosmological observations. Any model that can
support such a coasting presents itself as a falsifiable model as far as
classical cosmological tests are concerned. Such evolution is known to be
comfortably concordant with the Hubble diagram as deduced from data of recent
supernovae 1a and high redshift objects, it passes constraints arising from the
age and gravitational lensing statistics and clears basic constraints on
nucleosynthesis. Such an evolution exhibits distinguishable and verifiable
features for the recombination era. This article discusses the concordance of
such an evolution in relation to minimal requirements for large scale structure
formation and cosmic microwave background anisotropy along with the overall
viability of such models.
  While these results should be of interest for a host of alternative gravity
models that support a linear coasting, we conjecture that a linear evolution
would emerge naturally either from General Relativity itself or from a General
Relativistic theory of a non-minimally coupled scalar field theory.
