Reallocation of a capacity boost cell between first and second operators in a cellular radio communications network is carried out by detecting a drop in load for the first operator, in the area of coverage of the capacity boost cell, below a first threshold, and reallocating automatically the capacity boost cell to the second operator in response to the detected drop in load, if the first operator has authorised a reallocation. The capacity boost cell can be reallocated automatically back to the first operator in response to detecting a subsequent increase in load above a second threshold for the first operator. This can improve utilisation of the capacity boost cell during low load periods while still having it available for the first operator for high load periods, and can provide access to additional capacity for the second operator without need for costly additional infrastructure.