Add 3.275m to data values for 1943 to refer to RLR<br>Add 3.275m to data values for 1943 to refer to RLR<br>Add 3.275m to data values for 1963 to refer to RLR<br>Add 3.275m to data values 1963 onwards to refer to RLR<br>RLR is 12.500m below primary benchmark BM NGF NPQ 35