This specific Dalek was apparently the first ever Dalek made as it was used by the insane and evil scientist Davros to show it off to all the Kaled leaders and sceintists as well as the Doctor who had got caghut up in the crowd. The Test Dalek is at first controlled by remote control by Davros but as soon as he turns it off the Dalek notices the Doctor lurking in the crowd and sets fourth to kill him but the gun didnt yet work so there was luckily enough time to shut it down. This Dalek is presumeably bourght back for the Dalek revolt and is destroyed when the Kaled bunker was blown up.