Upper frame – phase versus flux density plot of HD 133880 at 1.4 GHz (red colour) and 610 MHz (blue colour). Here red squares denote GMRT 1390 MHz measurements, red diamonds denote VLA 1.4 GHz measurements, blue squares denote GMRT 610 MHz observations made by us in 2014 January, whereas the blue diamonds are the 2009 December data of George & Stevens (2012) reanalysed by us. Note that unlike in Figs 1 and 2, the vertical scale in this figure is logarithmic. Lower frame – longitudinal magnetic field variation of HD 133880, from Bailey et al. (2012). The vertical lines in both plots indicate phases 0.25 and 0.75.