Fraction of all multi-wavelength sources that host a LOFAR source in ELAIS-N1 as a function of (i - 4.5) colour. The size of the data points corresponds to number of LOFAR sources within that colour bin (indicated by the adjacent number), and the colour of the points is a proxy for counterpart colour. The reddest galaxies are more than an order of magnitude more likely to host a radio source than the bluest of galaxies.