All circuit of neon tube light is like this: L(live), inductor, first heater, starter, second heater, N(neutral) connected in series. Starter is gas glow bulb where one of electrodes is made of bi-metal, and parallel capacitor for RFI. When you switch on starter bulb is short circuited and heating current flows through series circuit. After some time (few second) gas bulb is heated enough and bi-metal electrode break the series circuit. Sudden reduce in circuit current causes induction of high voltage on inductor and so on the opposite electrodes of neon tube. Neon tube starts to glow giving the light. At the same time the starter bulb continue to glow and keep hot preventing bi-metal electrode to close again. Start of neon tube may be clean or through few attempts (flickering). Inductor limits the neon tube voltage when it glows to abt. 50V.