A method of communicating data between a base station and a plurality of terminal devices in a wireless telecommunications system. The method comprises transmitting data from the base station to the plurality of terminal devices in a multicast transmission and transmitting response signals from the terminal devices to the base station to indicate whether the respective terminal devices have successfully received the multicast transmission. The use of a multicast transmission provides an efficient mechanism for communicating the same data to a plurality of terminal device, for example as might be desired in a machine-type communication network. In combination with this, the use of individual response signals, such as ACK/NACK signalling, from the terminal devices allows the base station, or other entity, such as a machine-type communications server, to track which terminal devices have indicated successful receipt of the multicast transmission, and to instigate an appropriate re-transmission protocol accordingly.