Network infrastructure equipment for use in in a wireless telecommunications system for communicating an indication of an allocation of radio resources on a radio channel for communicating data between the network infrastructure equipment and a terminal device (506, 508), wherein the radio channel spans a channel frequency bandwidth divided into frequency resource units which may be selectively allocated for communicating data between the network infrastructure equipment and the terminal device, wherein the network infrastructure equipment comprises controller circuitry and transceiver circuitry configured to operate together such that the network infrastructure equipment is operable to: select a combination of the resource units for communicating the data between the network infrastructure equipment and the terminal device from among a predefined set of allowable combinations of the resource units, wherein the set of the allowable combinations of the resource units is restricted to a number of allowable combinations of the resource units that is smaller than the total number of possible combinations of the resource units and which includes non-contiguous combinations of the resource units, establish an indication of the selected combination of the resource units; and transmit the indication of the selected combination of the resource units to the terminal device; wherein the radio channel is one of a plurality of narrowband or wide bandwidth narrowband, WB-NB, channels supported within a wider system bandwidth of the wireless telecommunications system, and wherein the indication of the selected combination of the resource units includes an indication of which one of the plurality of narrowband or WB-NB channels contains the selected combination of the resource units; and characterized in that the radio channel is notionally divided into a plurality of sub-channels, wherein each sub-channel comprises a plurality of resource units, and wherein the indication of the selected combination of the resource units comprises an indication of which one or more of the sub-channels contains resource units in the selected combination of the resource units; wherein the indication of the selected combination of the resource units to the terminal device comprises a number of data bits indicating which of the notional sub-channels contains resource units in the selected combination of the resource units, the number of data bits being selected to allow resource units in any combination of the plurality of notional sub-channels to be allocated. select a combination of the resource units for communicating the data between the network infrastructure equipment and the terminal device from among a predefined set of allowable combinations of the resource units, wherein the set of the allowable combinations of the resource units is restricted to a number of allowable combinations of the resource units that is smaller than the total number of possible combinations of the resource units and which includes non-contiguous combinations of the resource units, establish an indication of the selected combination of the resource units; and transmit the indication of the selected combination of the resource units to the terminal device; wherein the radio channel is one of a plurality of narrowband or wide bandwidth narrowband, WB-NB, channels supported within a wider system bandwidth of the wireless telecommunications system, and wherein the indication of the selected combination of the resource units includes an indication of which one of the plurality of narrowband or WB-NB channels contains the selected combination of the resource units; and characterized in that the radio channel is notionally divided into a plurality of sub-channels, wherein each sub-channel comprises a plurality of resource units, and wherein the indication of the selected combination of the resource units comprises an indication of which one or more of the sub-channels contains resource units in the selected combination of the resource units; wherein the indication of the selected combination of the resource units to the terminal device comprises a number of data bits indicating which of the notional sub-channels contains resource units in the selected combination of the resource units, the number of data bits being selected to allow resource units in any combination of the plurality of notional sub-channels to be allocated.