The study of high redshift (z ~> 1) dusty star-forming galaxies, known as Submillimetre Galaxies (SMGs), has been hampered by the flux-limited single dish surveys used for their initial detection, meaning that only the most infrared luminous of this galaxy population are identified. With the aim of circumventing this bias this project uses the Triple Colour Cut approach which selects candidate SMG counterparts from their optical and near-infrared colours. This technique was used to identify 57 SMGs which form the final main catalogue and was extended to identify a further 62 SMGs which form the final supplementary catalogue. The SMG candidates identified are more modestly infrared luminous than populations identified using other counterpart detection methods, with a median infrared luminosity of log (L_IR / L_o) ~ 12.19 +/- 0.09 and median star formation rate of ~ (147 +/- 28) M_o yr^ -1 . The median photometric redshift for this sample is estimated to be z_phot ~ 2.75 +0.09/-0.08 , with a distribution which dips at z_phot ~ 2.4. To investigate the AGN fraction this project applied 3 contrasting AGN classification methods, using X-ray luminosity, radio luminosity and IRAC colours to classify ~ 29% of SMGs as AGN hosts. Aside from having estimated median infrared luminosities and star formation rates which are a factor of ~ 3 higher, AGN host SMGs were found to have similar physical properties to non-AGN hosts.