  The linear polarisation fraction and angle of the hard X-ray emission from
the Crab provide unique insight into high energy radiation mechanisms,
complementing the usual imaging, timing and spectroscopic approaches. Results
have recently been presented by two missions operating in partially overlapping
energy bands, PoGO+ (18-160 keV) and AstroSat CZTI (100-380 keV). We previously
reported PoGO+ results on the polarisation parameters integrated across the
light-curve and for the entire nebula-dominated off-pulse region. We now
introduce finer phase binning, in light of the AstroSat CZTI claim that the
polarisation fraction varies across the off-pulse region. Since both missions
are operating in a regime where errors on the reconstructed polarisation
parameters are non-Gaussian, we adopt a Bayesian approach to compare results
from each mission. We find no statistically significant variation in off-pulse
polarisation parameters, neither when considering the mission data separately
nor when they are combined. This supports expectations from standard
high-energy emission models.
