I take that it would extinguish due to lack of current flow of the arc tube

I need a proper ballast. Will it go to full brightness?

You can also use two or more lower wattage ballasts running in parallel.

How long is the arc tube? Maybe Yoda can use this as his Lightsabre by the look of it

No the US 1000 watt Mercury runs different then a European 1000 watt Mercury, example the US lamp operates at 4 amps 265 volts where the European Mercury Lamp operates at 7.75 amps 145 volts, using the 400 watt Ballast is OK as for the Lamp Current but as the Lamp warms up the voltage will rise and will cause the lamp to go out, if you want a proper Ballast you need to try and find a H36 1000w Mercury Ballast or a US M47 Metal Halide Ballast, E-bay is the best place as some are listed cheap.

If like me you like in Europe, a 1000w Mercury Ballast is a simple Reactance Ballast (Choke), and if you don't have one you could connect 2 Ballasts In Parallel , but the Lamp will be slightly under run as running on 2 x 400w Mercury/Metal Halide Ballasts in Parallel the Lamp will run at 135 volts 6.5 amps not the 145 volts 7.75 amps.

this also applies to the 700 watt Mercury Lamp as in the USA, the 700 watt Mercury Lamp operates at 260 volts 2.8 amps and operates on a H35 Mercury Ballast Only, where the European 700 watt Mercury Lamp operates at 140 volts 5.4 amps and will operate on either a 700w Mercury Ballast or a 400 watt and 250 watt Mercury Ballasts in Parallel on the 400 and 250w circuit the European Mercury Lamp runs at 135 volts 5.38 amps slightly under run with no effect to lamp or Ballasts.

Do Euro choke ballasts draw more current during start up like US reactor and HX ballasts do? Overall I like the idea of a choke ballast, its simpler and more energy efficient. Europe does a good job with simplifying things; ie only 230/400Y in a building, no 120/208 and 277/480. Then you have things like high leg at the auto-repair down the street lol.

Everythings bigger in Texas

Yes, European Lamps are designed with a Lower Voltage / Higher Current Arc Tubes, as most Discharge Lamps require minimum of 200 volts to work, they can be wired on a simple Reactance Ballast (Choke), where in the USA most supplies at 120 volts you need a Reactor Ballast which is Both a Transformer to raise the Voltage, and a Ballast to stabilise the current for the Lamp. but also in the USA for the 35 to 150 watt High Pressure Sodium Lamps, they are made with a 52 to 55 volt Arc Tube for use on a simple Reactance Ballast (Choke). but with them having a lower voltage Arc Tube they have a Higher Current Arc Tube, compared to the European High Pressure Sodium Lamp, example a US S55 150 watt High Pressure Sodium Lamp operates a 55 volts 3.10 amps, where a European 150 watt High Pressure Sodium Lamp operates at 100 volts 1.8 amps, this is the same for the US S56 150w High Pressure Sodium Lamp, so are interchangeable on Both the US S56 Gear and the European 150w HPS/MH Gear.