I took Helen on her longest walk yet, doing a near three mile circular walk in the Chilterns along with my friend Cathy and her six and nine year old daughters.
The route was the southern circular walk in a "Chilterns Country" Box Wood walks pamphlet (with the only modification that we took a short cut from point 10 to point 12, which probably dropped the distance to 2.7 miles or so).
This is a really lovely walk. I selected it as suitable for a three and a half year old, but it's actually just a great walk, which I'd happily take overseas visitors or anyone else on. One big attraction is that most of it is under trees. We didn't get into the box woodland, but Pulpit Hill is well forested (though it was kept clear back in the Iron Age when it was a hill fort) and the beech forest of Ninn Wood is fantastic. There are a couple of fifty metre climbs, just enough to test out little legs a bit. There's one very short stretch on a busy B road with no verges or footpaths, but otherwise the walk is on tracks and permissive routes with no motor traffic at all. And two thirds of the way through the walk is a nice spot for lunch, the Plough at Cadsden. (A child-friendly feature is that there are several possible shortcuts; bailing out at the Plough would also be feasible.)
We had what I consider perfect walking weather - overcast but dry, with temperatures climbing from 15 towards 19. As a special bonus, we encountered some friendly Chiltern Rangers doing work for the National Trust, putting in a new fence. One of them gave us a brief run-down on the history and geology of the area, and then they let the three kids sit in the tractor for a bit!
There was remarkably little complaining (and what there was of that came early on, perhaps helped along by some nasty scratches from some blackberries). Helen ran more than half of the last mile - perhaps inspired by the nine year old, who was a keen runner - and seemed perfectly capable of doing more when we reached the cars. So I think I can add 3.5 and 4 mile walks to my walk search: the northern circular walk here is certainly a candidate, but even just repeating this walk would be pretty tempting.