Left panel shows standardised (by mean and standard deviation calculated over common 1985–2014 base period) and smoothed (by locally weighted regression smoothing (Loess) using a span =15 years) series (between 1961 and 2014) following Hannaford et al. (2013a) for low (Q95), medium (Q50 and AMF), and high flow (Q05) indices defined in the Hydrological indicators and catchment selection section. Solid grey lines are individual stations; dotted lines are the 5th and 95th percentiles across all stations, and solid black line the mean (1961 deemed earliest year to reliably calculate percentiles). Right panel shows persistence of trends in the same indices alternating all available start years between 1930 and 2014, 1931 and 2014, and so on up to 2000–2014 using MKZs following Wilby (2006). Solid grey lines represent MKZs statistics for varying start years for individual stations across the UK. Dashed horizontal lines are the threshold for statistically significant trends at the 5% level with MKZs values above (below) these indicating statistically significant increasing (decreasing) trends since the corresponding start year. In both panels, black dotted vertical lines mark start years of the two fixed periods used in the present analysis for context.