  The surface brightness -- colour relation (SBCR) is a basic tool in
establishing precise and accurate distances within the Local Group. Detached
eclipsing binary stars with accurately determined radii and trigonometric
parallaxes allow for a calibration of the SBCRs with unprecedented accuracy. We
analysed four nearby eclipsing binary stars containing late F-type main
sequence components: AL Ari, AL Dor, FM Leo and BN Scl. We determined very
precise spectroscopic orbits and combined them with high precision ground- and
space-based photometry. We derived the astrophysical parameters of their
components with mean errors of 0.1% for mass and 0.4% for radius. We combined
those four systems with another 24 nearby eclipsing binaries with accurately
known radii from the literature for which $Gaia$ EDR3 parallaxes are available,
in order to derive the SBCRs. The resulting SBCRs cover stellar spectral types
from B9 V to G7 V. For calibrations we used Johnson optical $B$ and $V$, $Gaia$
$G_{\rm BP}$ and $G$ and 2MASS $JHK$ bands. The most precise relations are
calibrated using the infrared $K$ band and allow to predict angular diameters
of A-, F-, and G-type dwarf and subgiant stars with a precision of 1%.
