Fitting a battery in the engine bay

[CJH]

My van is a 1.9DG, so the starter battery is in the box behind the driver's seat. My leisure battery is in the box behind the passenger seat. I've got a spare (starter*) battery, and I'd like to put it in the space in the rear left corner of the engine bay, from where it'll be a fairly short cable run to a changeover switch near my CTEK charging system in the wardrobe.

So simple question: Is there a standard bracket that I can add to hold the battery still in that position? Did some vans have the battery there from the factory, and if so what did they use to hold it still?

*E D I T: Just to be clear - it's a 'starter' battery that I'm going to use as a second leisure battery.