A terminal device for use in a wireless telecommunications system comprises a transceiver to perform wireless communication with a base station and to obtain system information defining communication parameters from system information data received from that base station; system information storage; and a controller to detect whether the system information storage already holds at least some of the system information applicable to a newly communicating base station and to control the transceiver to obtain any portions of the system information not already held by the terminal device, in which: the system information comprises a plurality of system information blocks; and the controller is configured to detect parts of a system information block stored by the system information storage which are applicable to the newly communicating base station and to obtain other parts of that system information block as a partial system information block from the newly communicating base station.