VPHAS+ image of the Lagoon nebula (size 55.8′ × 34.8′, corresponding to 20.36 × 12.7 pc), with superimposed all Gaia-ESO target positions used in this work. Giraffe targets are indicated with magenta (sky fibres) or orange (faint stars) filled squares.UVES sky fibres are indicated with red (setup 580) or green (setup 520) filled squares. Only one UVES-580 sky fibre position is not coincident with (and its symbol not hidden by) an UVES-520 sky fibre position.UVES stars are indicated with red crosses (setup 580) or blue “+” signs (setup 520). Red triangles indicate the O stars HD 165246, HD 165052, HD 164816, 9 Sgr, Herschel 36, and HD 164536. Green triangles indicate the massive objects M 8E-IR, HD 164865, and 7 Sgr. North is up and east to the left.