The ageing responses of surface/centre layer materials from a commercially produced AA7150 thick plate have been studied after both water quenching (WQ) and air cooling (AC). The results show that the higher degree of recrystallisation near the plate surface decreases its age hardening response in AC condition. Quench-induced phases have been found to precipitate preferentially on Al3Zr dispersoids in recrystallised grains. Micro-structural observations show that Al3Zr dispersoids in recrystallised grains exhibit the same crystal structure and orientation as those in adjacent subgrains.