Discharge optimisation for improving MHD stability of both core and edge was essential for the achievement of record fusion power discharges, in the ELM-free hot-ion H-mode regime, in the recent JET deuterium-tritium operation. In this paper the techniques used to increase edge stability are described. In particular the paper reports on the successful technique of current ramp-down used to suppress the outer mode. The increased stability of the outer mode by decreasing the edge current density confirms its identification as an n=1 external kink [1]. Decreasing the plasma current, however, decreases the ELM-free period, which is consistent with stability calculations that show an earlier onset of the ballooning limit. In order to increase external kink stability without deteriorating the ELM-free period, a compromise was achieved by using plasma current ramp-down, while working at the highest plasma current values possible. Results from a plasma current scan show that at the time of occurrence of the first giant ELM, the plasma stored energy as well as the pressure measured at the top of the edge pedestal increase linearly with plasma current, for a given plasma configuration and power. This is consistent with models of the edge transport barrier, where the transport barrier width is proportional to the ion (or fast ion) poloidal Larmor radius. The MHD observations in deuterium-tritium and deuterium only discharges were found to be similar. Thus the experience gained on the control of MHD modes in deuterium plasmas could be fully exploited in the deuterium-tritium campaign.