LoveHoney sizes are based on the sizes that are given in the stockists books. If you look at Dreamgirl sizes for instance, they are very different to What Katie Did sizes and different again from Music Legs sizes. This is why all the pages have sizing guides so you know which to order.
If you go into Gap or Topshop a 'small' is generally a size 6/8 so we tend to stick to convention and call a spade a spade (or a size 8 a small, as it were) just for ease of identifying really. When people are used to convention, its easier to stick to it than be radical and start calling a size 16 a small as we'd then have to go down to extra extra extra extra small in the case of sizes 6/8, which is confusing and wouldn't fit on the label!
We actually have a massive range of 'plus size lingerie' which tends to go overlooked by people but it actually contains some beautiful pieces of lingerie and the occasional exclusive piece which is only available in plus sizes.
We're actually looking to go bigger than size 26 in our lingerie range but its just a matter of finding a good, reliable, high quality supplier that makes genuinely sexy clothes!