  We present an investigation of candidate Infrared Dark Cloud cores as
identified by Simon et al. (2006) located within the SCUBA Legacy Catalogue.
After applying a uniform noise cut to the Catalogue data we identify 154
Infrared Dark Cloud cores that were detected at 850um and 51 cores that were
not. We derive column densities for each core from their 8um extinction and
find that the IRDCs detected at 850um have higher column densities (a mean of
1.7x10^22 cm-2) compared to those cores not detected at 850um (a mean of
1.0x10^22 cm-2). Combined with sensitivity estimates, we suggest that the cores
not detected at 850um are low mass, low column density and low temperature
cores that are below the sensitivity limit of SCUBA at 850um. For a subsample
of the cores detected at 850um those contained within the MIPSGAL area) we find
that two thirds are associated with 24um sources. Cores not associated with
24um emission are either ``starless'' IRDC cores that perhaps have yet to form
stars, or contain low mass YSOs below the MIPSGAL detection limit. We see that
those ``starless'' IRDC cores and the IRDC cores associated with 24um emission
are drawn from the same column density population and are of similar mass. If
we then assume the cores without 24um embedded sources are at an earlier
evolutionary stage to cores with embedded objects we derive a statistical
lifetime for the quiescent phase of a few 10^3-10^4 years. Finally, we make
conservative predictions for the number of observed IRDCs that will be observed
by the Apex Telescope Galactic Plane Survey (ATLASGAL), the Herschel Infrared
Galactic Plane Survey (Hi-GAL), the JCMT Galactic Plane Survey (JPS) and the
SCUBA-2 ``All Sky'' Survey (SASSy).
