A method of operating a terminal device to perform measurement event evaluation for measurement reporting in respect of a downlink carrier in a wireless telecommunications system. The method includes determining that measurement event evaluation for the downlink carrier should be undertaken. Measurements of a parameter associated with radio channel conditions for frequency resources used by the downlink carrier are obtained during an evaluation period beginning at a start time. The extent to which the downlink carrier is being transmitted during the evaluation period is also established. Whether or not to send a measurement report to network infrastructure equipment is then evaluated by taking account of both the measurements of the parameter during the evaluation period and the extent to which the downlink carrier is being transmitted during the evaluation period.