DIY 400w MBF & MBI Gearbox V2.0

I was bored and decided that I should upgrade the 400w MBF ballast box that I cobbled together years ago into something a bit more useful.
Aside from housing the Philips BHL 400 k307 and PFC capacitor in a new enclosure, I have added a Philips SI51 parallel ignitor to the circuit which is triggered by a non-latching toggle switch.
This allows the use of metal halide lamps which are rated for use on a mercury vapour ballast.