  We fit a functional form for a universal ICM entropy profile to the scaled
entropy profiles of a catalogue of X-ray galaxy cluster outskirts results,
which are all relaxed cool core clusters at redshift below 0.25. We also
investigate the functional form suggested by Lapi et al. and Cavaliere et al.
for the behaviour of the entropy profile in the outskirts and find it to fit
the data well outside 0.3r200 . We highlight the discrepancy in the entropy
profile behaviour in the outskirts between observations and the numerical
simulations of Burns et al., and show that the entropy profile flattening due
to gas clumping calculated by Nagai & Lau is insufficient to match
observations, suggesting that gas clumping alone cannot be responsible for all
of the entropy profile flattening in the cluster outskirts. The entropy
profiles found with Suzaku are found to be consistent with ROSAT, XMM-Newton
and Planck results.
