It sounds as though the botanical garden of the South London Botanical Institute may be threatened by development. According to BGCI the garden has a particularly important collection of Rubus. The institute’s website mentions a Medicinal Border, Gerard’s Border, a Southern Hemisphere Area, and also that
British natives, ferns, scented plants, drought tolerant plants, monocots and unusual vegetables are also represented.
So some agricultural biodiversity is involved here, though I do not know to what extent the “unusual vegetables” and Rubus species, say, are to be found in other genebanks and botanical gardens. In any case, if you think losing this garden would be a bad idea, you can sign a petition. Fingers crossed.