  Concatenating data from the millimetre regime to the infrared, we have
performed spectral energy distribution modelling for 227 of the 405 millimetre
continuum sources of Hill et al. (2005) which are thought to contain young
massive stars in the earliest stages of their formation. Three main parameters
are extracted from the fits: temperature, mass and luminosity. The method
employed was Bayesian inference, which allows a statistically probable range of
suitable values for each parameter to be drawn for each individual protostellar
candidate. This is the first application of this method to massive star
formation.
  The cumulative distribution plots of the SED modelled parameters in this work
indicate that collectively, the sources without methanol maser and/or radio
continuum associations (MM-only cores) display similar characteristics to those
of high mass star formation regions. Attributing significance to the marginal
distinctions between the MM-only cores and the high-mass star formation sample
we draw hypotheses regarding the nature of the MM-only cores, including the
possibility that the population itself is comprised of different types of
source, and discuss their role in the formation scenarios of massive star
formation. In addition, we discuss the usefulness and limitations of SED
modelling and its application to the field. From this work, it is clear that
within the valid parameter ranges, SEDs utilising current far-infrared data can
not be used to determine the evolution of massive protostars or massive young
stellar objects.
