Yes, I've found that for me 'wilderness' was initially a tricky term to use in the UK.

As an explanation for anyone else reading: conservation in NZ and the UK are very different. In many areas of the UK, conservation consists partly of maintaining farming practices in the manner they've been practised in these places for hundreds (sometimes tens of hundreds) of years. Which, for a New Zealander, is totally bizarre. In New Zealand, there are gigantic swathes of somewhat-pristine forest (missing mostly birds, and some insects) we can look to as a model for conservation. Farmland and conservation are pretty much mutually exclusive.

So, in the UK you might use the term wilderness for a large, very lightly farmed, very lightly populated area. Where in NZ you mightn't use the term wilderness until you'd walked for half a day from civilisation.

Yeah, when I lived in the UK I was surprised by how much open space there was.

The cities and towns are better designed than those of new world countries which sprawl.

The old—even ancient—cities of Europe avoided the mistake of suburban building and have a naturally high-density shape from having been built before the automobile.

It's not visible in the center of cities, but an urban sprawl has developed on the periphery of cities. Such sprawls are similar to those existing in the US (car mandatory, few or no services, little public transportation).

the UK has the green belt system to try to prevent this happening

https://en.wikipedia.org/wiki/Green_belt_(United_Kingdom)

if anything it's too successful

As an aside (with apologies for sloppy definitions), I understand that the UK is about 0.1% densely built on (more than 80% of ground covered by artifical surface), and about 5.5% urban.

I understand this is much, much less than people typically think, which isn't just an interesting fact; people base their opinions on development on the unchecked feeling that the UK is 50% concrete.

Visit the Highlands of Scotland and you'll definitely find wilderness. The Cape Wrath trail is probably the best indicator. Also places like Beinn Eighe, where the remains of a crashed Lancaster bomber from 1951 are still scattered about as it is was too remote to retrieve them at the time. In 2008 a climber fell during an avalanche only to have his fall broken by a propeller.