Size matters. For a good run or a decent kickabout, it helps if you live near a park with a footprint of at least 35 acres.
"A sprawling North London parkland...that encompasses the city’s highest point and spreads far beyond it...that has a shade of green for every possible felicitation of light." (Zadie Smith on Hampstead Heath)
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The third (and final) contributor to our aggregate "leafiness" metric derives from a measurement of the proximity of each postcode to the nearest "large park", where the latter is defined as any publicly accessible park with a footprint of at least 35 acres. There are 202 of these large parks; and details of their acreage and perimeter are shown in the map below. In the notes below the map, we include additional commentary on the methodology used to calculate park proximity.
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To see the acreage and perimeter of any of the parks shown in the map above, hover your cursor over the park (or click on the park if you are using a mobile device). This will trigger a small lightbox showing these details, together with the park's nodal postcode.
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For our "park access" measure, we first had to plot all the vertices of the large parks (which, to recap, are those parks with areas of 35 acres or more). The sum total of these vertices is 18,432. For each of the 178,651 postcodes in London, we then ran a distance matrix to ascertain the closest "large-park" vertex and the distance thereto. For each of the 2,915 hexagons into which we have divided London, we then recorded the average value of these postcode-to-park-vertex distances and ranked the hexagons accordingly. Thus, hexagons in the top tier on our "park access" measure were the ones whose inhabitants were closest to a large publicly accessible park, whilst those in the bottom tier were those who residents were furthest from a large park.
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It is important to reiterate, however, that "park access" is only a one-third contributor to the aggregate "leafiness" metric used in the Polymap and the Gallery. Hence, readers need to be fully cognisant of the other two components, viz. the GVI score and the Green Space score.
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