  We characterise the variability in the physical properties of the luminous
blue variable AFGL2298 between 1989-2008. In conjunction with published data
from 1989-2001, we have undertaken a long term (2001-2008) near-IR
spectroscopic and photometric observational campaign for this star and utilise
a non-LTE model atmosphere code to interpret these data. We find AFGL2298 to
have been highly variable during the two decades covered by the observational
datasets. Photometric variations of >1.6 mag have been observed in the JHK
wavebands; however, these are not accompanied by correlated changes in near-IR
colour. Non-LTE model atmosphere analysis of 4 epochs of K band spectroscopy
obtained between 2001-7 suggests that the photometric changes were driven by
expansion and contraction of the stellar photosphere accompanied by
comparatively small changes in the stellar temperature. Unclumped mass loss
rates throughout this period were modest and directly comparable to those of
other highly luminous LBVs. However, the bolometric luminosity of AFGL2298
appears to have varied by at least a factor of ~2 between 1989-2008, with it
being one of the most luminous stars in the Galaxy during maximum. Comparison
to other LBVs that have undergone non bolometric luminosity conserving
`eruptions' shows such events to be heterogeneous, with AFGL2298 the least
extreme example. These results - and the diverse nature of both the quiescent
LBVs and associated ejecta - may offer support to the suggestion that more than
one physical mechanism is responsible for such behaviour. [ABRIDGED]
