If you were asked 'what percentage of UK land is actually urban?', how would you answer? Would you respond like the average Brit and say about 50%? Or would you go even higher?

There are, of course, very specific definitions of what 'urban' actually means, including quite arcane differences between what the academics refer to as either 'continuous urban fabric' (CUF) or 'discontinuous urban fabric' (DUF). But you get the idea: it's the built-up bits.

Professor Alisdair Rae at the University of Sheffield produced his report on this very subject back in 2017 and it does actually contain the definitive answer, which I will reveal a little bit later.

I was mulling over this question when I recently cycled through one of our most overlooked and yet sublime local landscapes, one that sits within easy striking distance of two local examples of both CUF & DUF: Hitchin and Luton, which between them boast a population of some 236,000 people. The juxtaposition was somewhat hard to comprehend.

We have a couple of named 'bottoms' in our area- in this context it simply means a valley floor- all of which are to be found in the gently rolling hills south and west of Hitchin: Kimpton Bottom, Langley Bottom, Codicote Bottom, Whiteway Bottom and today's chosen subject, Lilley Bottom.

Lilley Bottom is three miles long, stretching from the bridge across the A505 in Lilley to Stagenhoe Bottom Farm near Whitwell. But before you set off to explore its full length, a word of warning may be needed: the busy road that follows the valley is no place for the rambler, what with speeding cars, hurtling delivery vans and bristling farm machinery vying for dominance.

However, not being able to stroll along the bottom of the bottom is no real obstacle to its exploration as there is much to enjoy by using any one of the useful footpaths and bridleways that regularly crisscross this broad valley.

These rights-of-way are all detailed on the OS Explorer 193 map, but you could also try using your smartphone to plan a fine circular route; both Offley and Kings Walden are good starting places for such expeditions to explore 'the other side'.

As this is classic chalk country, we would be foolish to expect any towering cliffs or steep slopes. But what we do get by way of compensation is a gentle rolling landscape, possessed of a quiet understated beauty that would be no doubt familiar to artists such as Paul Nash and Eric Revilious.

Both sides of the valley host prime mixed agricultural land, dotted with farms and fields of every shape and size. Incidentally, many of these were worked by Italian POWs at the end of WWII and enduring friendships were forged with the friendly and grateful populace.

Woodland is also commonplace, both large and small, and as well as providing shelter for game birds, these add considerable interest to the landscape.

Some woods bear the name of now forgotten individuals: Watkin; Angel; Stubbock; Judkin; Lord; Thomas and Duxley et al, while others poetically describe their appearance, location or offer a hint at past usage: Plantation; Sallow; Limekiln; Garden; Hanger; Roundabouts and Rookery.

The majority of Lilley Bottom is now a dry valley, but may have at some time hosted a larger, more continuous river along its length, possibly at the end of the last ice age some 12,000 years ago.

Today it carries only the delightful and endangered Mimram, which rises at the bottom's most south-westerly point on the outskirts of Whitwell. From this modest source, the Mimram flows through Whitwell itself, through the splendid ford at Codicote Bottom and after passing under the Digswell Viaduct, its 12-mile journey is finally ended when it joins the River Lea at Hertford.

Although there may not be another river, Lilley Bottom still has other springs, some just half a mile or so from the Mimram's source.

You can see the location of these in a field just over the road from Bendish Lodge. As a 'winterbourne' these springs will only flow in periods of higher rainfall when the chalk aquifer is fully replenished. At such times a brace of small ponds may then appear.

Flooding of the valley floor and adjacent fields can also occur, and I can remember some significant puddles- almost miniature lakes- forming over the last twenty or thirty years.

This same aquifer also supplies local drinking water via the pumping station found below Kings Walden and the water company also uses its bore holes to monitor ground water levels, occasionally warning of an imminent flood risk.

The wildlife along Lilley Bottom is just as you would expect, with no real no surprises but plenty of brief but joyous encounters: I have seen deer, the occasional speeding hare, skulking daytime foxes and even sadly the occasional car-struck badger on my wanders.

But this valley does have a wildlife ace up its sleeve, resulting in me once jokingly referring to it as the 'Land of the Hawk', so numerous are both buzzards and red kites along its length. You would be unlucky not to see either when visiting.

Cages of kites often circle high above the tree line and if you are lucky, you could even have a more close-up encounter with a lone buzzard perching on a pole or a tree.

Even better, on fields at the Whitwell end of the bottom, you can often see kites actually touch down and loiter for a bit. On the ground their size and colouration are even more impressive, a sight that also attract flocks of twitchers with very large lenses, all eager to capture such a relatively unusual view of this conservation miracle.

And talking of views, do I hear you ask what my favourite view is of this broad and beautiful valley? No? Well here goes anyway: it is by some fine oaks at the top of the lane that runs from Lilley Bottom to Frogmore – map ref TL170228 TLW (intestine.beats.producers). And what a view it is, especially in sunshine: from here the full width is apparent, with the presence of distant Duxleys Wood and the nearer Law Hall Farm completing the picture.

But there are many other fine places to pause, reflect and marvel at the beauty to be found in the fine valley of Lilley Bottom, despite its close proximity to large populations.

And the surprisingly good news- according to Professor Rae's report mentioned at the beginning- is that only 5.4% of the UK can currently be considered as 'urban'. That is correct, less than 6% is built-up.

Yes, increasing populations will need more room, but by us all using and enjoying the remaining 94% in a wise and sustainable manner, these rural idylls on our doorstep- Like Lilley and all the other lovely bottoms- will be here for decades to come.

You know what to do.