  We use Subaru Suprime-Cam and VLT FORS1 photometry of the dwarf galaxy DDO210
to study the global stellar content and structural properties of a
transition-type galaxy (with properties intermediate between dwarf irregular
and dwarf spheroidal systems). This galaxy is sufficiently isolated that tidal
interactions are not likely to have affected its evolution in any way. The
colour-magnitude diagrams of DDO210 show a red giant branch (RGB) population
(with an RGB bump), a bright asymptotic giant branch population, a red clump,
young main sequence stars and blue-loop stars. The youngest stars formed within
the last 60 Myrs and have a distinct radial distribution compared to the main
population. Whereas the overall stellar spatial distribution and HI spatial
distribution are concentric, the young stars are offset from the center of
DDO210 and are coincident with a `dent' in the HI distribution. The implied
recent star formation rate required to form the young population is
significantly higher than the derived current star formation rate, by a factor
of > 10.
  Most of the stars in DDO210 are found in a red clump, and its mean I-band
magnitude suggests that the majority of stars in DDO210 have an average age of
4^{+2}_{-1} Gyr. Given this age, the colour of the RGB implies a mean
metallicity of [Fe/H] ~ -1.3. By comparing the shape of the red clump with
models for a variety of star formation histories, we estimate that an old (> 10
Gyr) stellar population can contribute ~ 20 - 30% of the stars in DDO210 at
most. The unusual star formation history of DDO210, its low mass estimate and
its isolated nature, provide insight into how star formation proceeds in the
lowest mass, unperturbed, dwarf galaxy haloes.
