ISIS spectropolarimetry of the continuum rebinned to 112 Å in the blue and 63 Å in the red (empty symbols joined by solid lines), and new DIPol-UF BBCP (solid circles) of three non-magnetic WDs. Star WD 1647+591 was observed three times with grating R600B, and observations obtained in different epochs are shown with different colours. The other two stars were observed simultaneously with gratings R600B and R1200R; see Bagnulo & Landstreet (2018) for more details. Data for different stars have been offset by 0, −0.2, and −0.4% for display purposes. Our BBCP measurements (zero polarisation) are consistent with no detectable magnetic field.