Keep three columns on the walk — remembered, observed today, not known — and test the green column against a figure before anyone argues. In 2018, green infrastructure covered 42% of the area of cities across the 38 EEA member countries on average, while publicly available green space averaged only 3% of city area, according to the EEA briefing on access to nature in cities published on 1 February 2022. The condition that changes the reading is the map: a green shape on a map is coverage, and coverage is not a place anyone can walk into.

Pick a short route both people can use, or start from a doorway or a window. Each person chooses one feature to follow: a street tree, a verge, a courtyard, the route to a park. The person who has known the street for forty years does not have to lead, and the person who arrived last year often sees what familiarity hides.

Three columns, one row per feature

Write one row per feature and fill all three columns before moving on. Remembered goes in the words the person used, with an honest date range — "around the time I moved here" is better evidence than a precise year invented to look tidy. Observed today carries the date, the clock time and the viewpoint. Not known carries the question, phrased so that a record could answer it. Where two memories disagree, keep both rows; a contradiction that survives the walk is worth more than an agreement reached by seniority. One person narrates and dates the memories; the other measures, photographs and writes, and they swap at the halfway point so both jobs get done by both people.

Test the green column against a number

Distance and size are the measurable part. England's Accessible Greenspace Standard sets a doorstep criterion of at least 0.5 hectares of accessible greenspace within 200 metres of home and a local criterion of at least 2 hectares within 300 metres, so a walk with a tape measure or a phone map settles part of the argument on the spot. Across Europe the picture from 2012 data was that fewer than half of the urban population lived within 300 metres of a park, ranging from more than 80% of Stockholm's population to under 20% in Heraklion, Greece, on the EEA's figures. Tree cover is a separate measurement again: the same briefing gives an average of 30% for cities across the EEA-38 in 2018, from 4% in Nicosia to 72% in Oslo.

Use those numbers as a scale, not as a verdict on your street. A European average applied to one road is the commonest mistake on a walk like this, and the local criterion you can actually test beats it every time; a greener street for whom works through that standard tier by tier.

A summer memory against a winter branch

Season decides what a single visit can show. A bare branch in February and a remembered July verge are both accurate and not comparable. The Nature's Calendar page on changing phenology reports spring advancing across Europe by 2.5 days per decade, and a Met Office estimate that the active growing season has run about a month longer during the past decade than it did between 1961 and 1990 — which is a reason to date every observation, not a reason to explain a single street with climate. Note the month beside each row and plan the return visit for the opposite season.

Example: the corner tree

Example. One person remembers a wider canopy at the corner in the 1970s. The other photographs one young tree there on 16 September and measures the walk to the park gate at 240 metres, with the park itself at 1.2 hectares. The 240 metres sits inside the 300-metre distance in the local criterion, but 1.2 hectares is below the 2 hectares that criterion asks for, so the street passes on distance and fails on size. The three columns then read: remembered, a larger canopy; observed, one young tree and a 1.2-hectare park 240 metres away, on 16 September; not known, when the previous tree was removed and what replaced it. Two of those three are checkable against a council tree record, and the third stays a memory with a date range, which is exactly what it is.

Finish by having each person write one sentence: "the change I can support", and "the question I still want answered". Keep the sheet for the return visit. Where the open question turns out to be about wildlife rather than kerbs, turning a local memory into a research question shows how to find out whether records for that period exist at all, and the seasonal comparison is worth doing properly with the repeatable definition in one place, four seasons.

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