Same system as in Fig. 19, but now showing the semi-major axes a of the planets as a function of time, colour coding in panel a the planets’ mass, in (b) the planetesimal surface density in the planets’ feeding zone, and in (c) the local gas surface density. Here, the vertical line indicates the moment of gas disc dissipation. Panel d: mass as a function of time, colour coding the semi-major axis. Small black circles indicate giant impacts, by showing the position or mass of the target (the more massive collision partner) at the moment of the impact.