  We describe the long-term evolution of a bipolar non-Hale active region which
was observed from October, 1995, to January, 1996. Along these four solar
rotations the sunspots and subsequent flux concentrations, during the decay
phase of the region, were observed to move in such a way that by December their
orientation conformed to the Hale-Nicholson polarity law. The sigmoidal shape
of the observed soft X-ray coronal loops allows us to determine the sense of
the twist in the magnetic configuration. This sense is confirmed by
extrapolating the observed photospheric magnetic field, using a linear
force-free approach, and comparing the shape of computed field lines to the
observed coronal loops. This sense of twist agrees with that of the dominant
helicity in the solar hemisphere where the region lies, as well as with the
evolution observed in the longitudinal magnetogram during the first rotation.
At first sight the relative motions of the spots may be miss-interpreted as the
rising of an $\Omega$-loop deformed by a kink-instability, but we deduce from
the sense of their relative displacements a handedness for the flux-tube axis
(writhe) which is opposite to that of the twist in the coronal loops and,
therefore, to what is expected for a kink-unstable flux-tube. After excluding
the kink instability, we interpret our observations in terms of a magnetic
flux-tube deformed by external motions while rising through the convective
zone. We compare our results with those of other related studies and we
discuss, in particular, whether the kink instability is relevant to explain the
peculiar evolution of some active regions.
