Farthing Downs and Happy Valley

Also within

Greater London CountySurrey County

Condition (Natural England)

Habitats

Ancient woodland, Mixed scrub, Montane scrub

Geology & landscape

Rock Type: Chalk

Description

Area, 120.5 ha. 297.8 ac. Description Farthing Downs and Happy Valley support the most extensive area of semi natural downland habitats remaining in Greater London. The site is of particular interest for its species rich chalk and neutral grasslands and for an area of ancient woodland known as Devilsden Wood. These habitats hold a large variety of herb species of restricted distribution in the County, including some which are nationally scarce. In addition the grasslands support the largest British colony of the nationally rare greater yellow rattle Rhinanthus angustifolius. The chalk of the North Downs comes to the surface over most of the site but is overlain by clay with flints on the western slopes of Happy Valley. The distribution of grassland and woodland communities reflects this variation in geology and the associated changes in soil types. The most diverse chalk grasslands occur on the thin rendzina soils on the eastern and north western sides of Happy Valley. The sward is dominated by upright brome Bromus erectus with quaking grass Briza media and other typical chalkland grasses. The herb flora is especially rich containing many species that are characteristic of unimproved chalk grassland but are of restricted occurrence in London owing to loss of this habitat. These include dwarf thistle Cirsium acaule, wild basil Clinopodium vulgare, horseshoe vetch Hippocrepis comosa, field scabious Knautia arvensis, common milkwort Polygala vulgaris, sainfoin Onobrychis viciifolia and hairy violet Viola hirta. These grasslands are also noted for their orchid flora with eight species being recorded, including the nationally scarce man orchid Orchis anthorpophora. Round headed rampion Phyteuma orbiculare, another nationally scarce plant, also occurs. The clay soils support a neutral grassland community. Sweet vernal grass Anthoxanthum odoratum and red fescue Festuca rubra are the most abundant grass species, with crested dog’s tail Cynosurus cristatus, tall fescue Schedonorus arundinaceus and a range of other meadow species. Amongst the rich herb component are meadow and bulbous buttercup Ranunculus acris and Ranunculus bulbosus, common sorrel Rumex acetosa and yellow rattle Rhinanthus minor. Woolly thistle Cirsium eriophorum, an uncommon species in the county is found on the lower slopes. The chalk grasslands of Farthing Downs have been disturbed by the encroachment and subsequent removal of thick scrub. In consequence the flora is intermediate between the chalk and neutral grasslands of Happy Valley. This area contains a large population of dropwort Filipendula vulgaris, an uncommon plant in London. All three grassland communities are of particular importance for the great abundance of greater yellow rattle. This plant is nationally rare and specially protected by legislation, being known from only six localities in great Britain. Farthing Downs and Happy Valley supports the major part of the total British population and is actively managed to safeguard and increase its abundance. Devilsden Wood lies on the western side of Happy Valley and straddles both chalk and clay soils. It has a high forest structure with ash Fraxinus excelsior, pedunculate oak Quercus robur and hazel Corylus avellana throughout. Over chalk, yew Taxus baccata features in the understorey with a diverse ground flora predominated by dog’s mercury Mercurialis perennis. Small groves of small beech Fagus sylvatica are also found here with white helleborine Cephalanthera damasonium, a scarce London plant, on the forest floor. The woodland over the clay with flints is distinguished by large stands of mature wild cherry Prunus avium. Species indicative of ancient woodland include midland hawthorn Crataegus monogyna, sweet woodruff Galium odoratum, bluebell Hyacinthoides non-scripta, yellow archangel Lamiastrum galeobdolon and bird’s nest orchid Neottia nidus-avis.

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities