  We present a study of Hen 2-155 and Hen 2-161, two planetary nebulae which
bear striking morphological similarities to other planetary nebulae known to
host close-binary central stars. Both central stars are revealed to be
photometric variables while spectroscopic observations confirm that Hen 2-155
is host to a double-eclipsing, post-common-envelope system with an orbital
period of 3h33m making it one of the shortest period binary central stars
known. The observations of Hen 2-161 are found to be consistent with a
post-common-envelope binary of period ~1 day.
  A detailed model of central star of Hen 2-155, is produced, showing the
nebular progenitor to be a hot, post-AGB remnant of approximately 0.62 Msol,
consistent with the age of the nebula, and the secondary star to be an M dwarf
whose radius is almost twice the expected ZAMS radius for its mass. In spite of
the small numbers, all main-sequence companions, of planetary nebulae central
stars, to have had their masses and radii constrained by both photometric and
spectroscopic observations have also been found to display this "inflation".
The cause of the "inflation" is uncertain but is probably related to rapid
accretion, immediately before the recent common-envelope phase, to which the
star has not yet thermally adjusted.
  The chemical composition of both nebulae is also analysed, showing both to
display elevated abundance discrepancy factors. This strengthens the link
between elevated abundance discrepancy factors and close binarity in the
nebular progenitor.
