In order to improve cooling of a blade 31, 41/disc 32, 42 combination, a pre-swirler feature 40, 50 is utilised in order to present coolant air through presentational pathways typically incorporating holes 37 or grooves/slots such that coolant air displaces hotter air leaked past a seal 35, 45. The swirler features 40, 50 are located within stationary housing components 34, 44 such that the coolant air is propelled at substantially the same rotational speed as the disc 32, 42 whilst presentation of the coolant air flow A, C, E is such that hot air displacement is achieved at least adjacent front faces 36, 46 of blade roots 33, 43.