We have investigated the radio emission from the anomalous X-ray pulsar 1E 1547.0–5408 ( PSR J1550–5418 ) using the Parkes telescope and the Australia Telescope Compact Array . The flux density of the pulsar is roughly the same between 1.4 and 45 GHz , but shows time variability . The radiation is nearly 100 % linearly polarized between frequencies of 45 and 3.2 GHz , but from 2.3 to 1.4 GHz it becomes increasingly more depolarized . The rotation measure of -1860 rad m ^ { -2 } is the largest for any known pulsar , and implies an average magnetic field strength along the line of sight of 2.7 \mu G. The pulse profiles are circularly polarized at all frequencies observed , more so at lower frequencies , at the \approx 15 \% level . The observed swing of the position angle of linear polarization as a function of pulse phase suggests that in this neutron star the rotation and magnetic axes are nearly aligned , and that its radio emission is only detectable within a small solid angle . Timing measurements indicate that the period derivative of this 2 s pulsar has increased by nearly 40 % in a 6-month period . The flat spectrum and variability in flux density and pulse profiles are reminiscent of the properties of XTE J1810–197 , the only other known radio-emitting magnetar , and are anomalous by comparison with those of ordinary radio pulsars .