The recent performance of the Daresbury Laboratory soft X-ray undulator beamline 5U1 is presented. The beamline resolution has been estimated from the photo-absorption of various gases. The resolution does not follow the expected trend with photon energy due to slope error problems with the optics. The flux has been measured by the drain-current from a gold photodiode and is in good agreement with the theoretical prediction. The performance of a new ellipsoidal post-focusing mirror is found to be in excellent agreement with the predictions from the ray tracing. The effect of movement of the source on photon energy calibration is considered.