I always thought the 303 had been banned in Australia, a contingency after the Japanese bombing and strafing of Darwin and hence the 22/303, 243/303, 25/303 and 270/303 cartridges based on the necked down 303 were developed.
The 303 was never banned here in NZ and cutdown or sporterized LE's and SMLE's were popular rifles for civilian and Government forest service culling use. The necked down 303 cartridges were all but unknown or at least unused here. Parker Hale produced three grades of sporterized versions of the SMLE which were very popular in NZ, I see them still coming up for second hand sale online occasionally.