This paper discusses the latest developments and results obtained from a field emission scanning transmission microscope. Some features of the instrument have already been described. The microscope has been in routine operation for more than two years at accelerating voltages of 80 and 100kV. Over this period a number of (111) and (310) oriented tungsten tips have been fitted and operated for varying periods in order to access the minimum lifetime to be expected. No tip has yet failed in service, and the (111) tip in current use has given more than 500 hours of stable and trouble free operation, in a vacuum of 3 to 5 x 10-11 torr.