Properties of the runaway candidates. Left: 2MASS near-infrared colour-colour diagram for the runaway candidates. The early type runaways originally from NGC 6611 in the last 3 Myr are shown in blue. Late type stars are highlighted in red and are deemed unlikely to come from NGC 6611. We show the location of the zero-age main-sequence in grey (Pecaut & Mamajek 2013). The reddening line for a B0 V (top) and M0 V star (bottom) are shown with the dashed black lines for R_V = 3.1 (Cardelli et al. 1989). Right: B, V and R composite mosaic image of NGC 6611 (ESO, press release 0926). We highlight the adopted search cluster search radius, with a radius of 0.1 deg (∼3 pc at a distance of 1.7 kpc), with the white circle. The trajectories of the O star runaways are shown in blue, while the B or later-type runaways are shown in orange. The ellipse shapes give the uncertainty on the location for the given trace-back time, which places the runaways near the centre of NGC 6611. The kinematic properties of these runaways are summarised in Table 2.