Watchhouse Hill is situated on the eastern edge of the village of Pill in North Somerset. It covers an area of approximately 10 hectares and is constrained to the north by the River Avon, the St Katherine’s Park housing development to the east and Parish football pitches to the south. The village and railway line forms its western boundary. The central grid reference for the site is ST 528 758.
The whole of the site is owned by North Somerset Council and managed by a volunteer group – the Friends of Watchhouse Hill. Section 106 money from the developers provides for any major works required and also routine maintenance. Any mowing or cutting is carried out by local farmer David Smith.
The northwest half of Watchhouse Hill has an undulating topography becoming steep in places. The main slope faces northwest with views across to Shirehampton and along the River Avon to the Severn Estuary. To the southwest, the site levels out to a flat plateau.
Underlying rock is keuper marl, a Triassic calcareous clay. Subsequent to the deposition of the marl, the site was overlain with a drift of gravel in the Pleistocene period.
The soils are a reddish fine loam which are prone to slight seasonal water logging where they overlie the clay but more free-draining where they overlie gravel.
The site has a diverse range of habitats coexisting together. Many of these habitats are old whilst others have been created more recently during the redevelopment of the hospital site.
Previously Watchhouse Hill was a mixture of farmland and the site of the old Ham Green Hospital which originated as an isolation unit moved from a hulk moored in the river .
The orchard that was planted to supply apples and pears to the hospital is now a community orchard.
The white house above right has an old mast as part of its stairs and the two chimneys visible in mid river mark the old Watch House
In the 1990s Redrow Homes (SW) Ltd submitted a planning application to develop the Ham Green Hospital site in February 1998.
The dominant grass species include Yorkshire fog, perennial rye-grass, cocksfoot, timothy, false oat-grass and rough meadow-grass. Wildflower species are poorly represented and limited to cut-leaved cranesbill, meadow buttercup, creeping buttercup, ribwort plantain, smooth hawksbeard, birdsfoot trefoil, white clover, hogweed, prickly sow-thistle, teasel, ground ivy, creeping thistle and dock.
The main field covers an area of approximately 2.80 hectares and prior to the development of the site field grazed by livestock and farmed relatively intensively with a moderate amount of fertiliser use. The field thus has an improved grassland sward, although this seems to be reverting to a poor semi-improved sward as perennial rye-grass is much less dominant now than when surveyed in 1996.
Bramble scrub tends to encroach from some of the field boundaries and controlled cutting takes place every two years any minor scattering of hawthorn scrub is also controlled in the main field by regular mowing and in other areas by three yearly cutting. There are a number of immature oaks in the northwest that have been left to mature and a dense belt of nettle beside the hedgerow in the south.
The field is crossed by one public right of way; the Avon Walkway Strategic Path, which runs from Pill to Bristol, cutting through the site before dropping back down to the River Avon which it follows through the Avon Gorge to Bristol. A number of natural desire lines have been opened-up by walkers providing other paths in this field and these are now mowed to prevent erosion caused by narrow walkways.
In 2009 a geophysical survey indicated that this could be the site of an iron age hill fort although excavations did not find any surrounding ditches other than farm boundaries. Some possible hut circles were indicated and further geophys investigation of these may be useful.