The present multi-pellet injector operating on JET is equipped with three repetitive pneumatic guns for three different pellet sizes capable of pellet speeds to 1 .5kms-1. It has nowbeen operated for more than one year according to its specification, satisfactorily and successfully, and only minor improvements have during that time. The best plasma performance in its application has so far been achieved with pellet deposition near the magnetic axis now possible only with relatively cold plasmas. For a given plasma the pellet speed is the only free parameter with regard to the penetration depth, since the pellet size determines the number of particles delivered to the plasma. In order to enable the central deposition also at higher plasma temperatures JET plans to employ an advanced gun system following the principles of hot pneumatics by adiabatic compression in two stage capable of launching initially single, and in a later version multiple, pellets with velocities towards the 5 to 10kms-1 range. We will describe here the present injector concentrating on the launcher machine interface and its upgrading the development programme directed to make a single pellet possible and the planning of the implementation of this prototype launcher, as well as briefly outline the preparations for a future multi-pellet launcher system following from the prototype.