I *love* stuff like this and I really want you to do well with your sale, but looking at the pics it would put me off buying the car.
Even though the price is reduced, 18k is still a chunk of money, and not being road registered significantly reduces any market of course.
But there's a few things that could be nicer in the pics. It all looks a bit tired, and the open inlets and general lack of any shine to anything just makes it look somewhat unloved ad forgotten about. It also doesn't look much like a westfield any more with the modified rear and big front spoiler, it's not going to appeal to a westfield owner because it's a westfield, it's going to appeal to a general sprinter looking for a powerful car, and someone who thinks they can do it justice (it looks a bit of an animal for many potential sprint / hillclimb car buyers I suspect).
The biggest thing for me though would be to get it a bit sparkly. Spending a weekend going round it with a tube of autosol, doing something about the hundreds of stone chips, replacing any visible rusty fasteners .. you might spend a grand on it, but at the moment it just looks unloved and un-cared for, which isn't what any buyer wants to see never mind someone potentially spending 18k on a car they can only use off road.
Hope you take that in the spirit it's intended, and best wishes / good luck with the sale.