Conduits and a pyramid at One Tree Hill

At the bottom of Maze Hill, just inside the park, we are presented with a complex array of conduits and water receivers, including a pond that no longer exists and a previously unknown pyramid by Nicholas Hawksmoor. The only visible remnant is the bricked-up entrance embraced by curving walls in the hillside, which is basically a small T-shaped conduit system which we have previously explored, surveyed and photographed (including a picture of the intact bricked-up entrance from inside - we have never found walls to be insuperable obstacles). A remarkable (and fragile) hand-coloured map in ink has recently come to light, which gives a highly accurate picture of the plumbing layout; its date is unknown. We publish a section of it here for the first time ever:

↑ Click for large version (624k 1000 x 915)

The Admiralty Survey of 1780 describes the (rather complicated) situation:

A little further eastward, the great leaden pipe aforesaid, turns through the trees to the south east, and at a certain place, divides again into 2 branches; one of which on the right hand, proceeds upwards in a diagonal line cross the lawn to a class of conduits on the north side of one tree Hill... At the east end of the avenue of trees, it receives a pipe of supply from the Conduit-head No.9, which conduit has a large brick drain, 50 feet in extent, toward the west, and another to the east, but turning round, passes afterwards to the south, into the side of the hill -

At the east end of the avenue aforesaid, the large leaden pipe has a branch of supply, from a Conduit head No.10 with a good supply of water from thence. This last conduit has a brick drain which passes underground a considerable way into the east side of the said hill -

At the east end of the avenue aforesaid, a pipe goes from the main leaden branch to a large brick building of a pyramidal form, entitled No.11, which building is nothing more than a receiver of a provisional supply from the main branch above mentioned, in case the supply of water, prove not sufficient, from a conduit head, No.12, standing a little up the hill to the south, and which conduit has a brick drain passing someway into the hill aforesaid -

In the receiver, No.11, there is only a small round basin, not capable of holding a quantity of water; and from thence a leaden pipe conveys the water to a house and garden in the north east...

The pyramidal structure is fascinating, especially given its antiquity; its demolition is scandalous. It is probably the square black structure with corner extensions on the plan above close to the roadway of Maze Hill, which is exactly at the location where Per von Scheibner discovered foundations some years ago. It should be thoroughly excavated, and if enough remains it should be fenced and an information board installed. Who designed it? Hawksmoor. He became Clerk of the Works at Greenwich in 1698, and began Castle Howard (with Vanbrugh) in 1699. Look at Castle Howard (first two photos) and his St Anne's Limehouse:





↑ First two photos provided by kind permission of yorkshirewalks.org Third photo author unknown (please contact me for a credit if it's yours).

↑ A map of 1827 shows three structures (arrowed) still standing, although how these relate to the plan above is uncertain.

Preserving the Greenwich Conduits

The Greenwich Conduits urgently need to be conserved and preserved. They are a remarkable and fascinating piece of the heritage of Greenwich which for too long have been neglected by the Royal Parks and mostly ignored by English Heritage¹ in terms of their structural maintenance and inspection. This must all stop. Now. It's time for the Royal Parks and English Heritage to welcome us into a thorough programme which will conserve and preserve these subterranean waterways, as well as launching investigations inside the park to locate the older Tudor sections cut off by Hawksmoor. It's also time to open at least one of the conduits to the general public, as has been done at the Coombe Conduit near Hampton Court, which enjoys open days organised and staffed by Kingston Upon Thames Society with the full support of English Heritage. We are very confident that there would be considerable public interest in going underground in the park.

Conduits in Greenwich park - above, in excellent condition, and below, neglected but still standing.



The Government document PPS5 Planning for the Historic Environment: Historic Environment Planning Practice Guide contains a number of pertinent paragraphs that the Royal Parks would be well advised to learn from and act on:

6. People care about and want to conserve those elements of the historic environment that hold heritage value for them. Once they are lost, they cannot be replaced. People also want the historic environment to be a living and integral part of their local scene. That requires proactive and intelligent management of heritage assets. Sometimes change will be desirable to facilitate viable uses that can provide for their long term conservation.

10. A key feature of the PPS is its holistic approach to the historic environment. The elements of the historic environment that are worthy of consideration in planning matters are called ‘heritage assets’. This term embraces all manner of features, including: buildings, parks and gardens, standing, buried and submerged remains, areas, sites and landscapes, whether designated or not and whether or not capable of designation.

74. Local planning authorities, developers and other stakeholders with an interest in the historic environment will often find it useful and/or necessary to seek the advice of appropriately qualified and experienced individuals or organisations. This may be, for example: to inform the plan-making process, to provide advice on the significance of a heritage asset, or to undertake an archaeological survey.

Re: 74: Per von Scheibner and Dominic Clinton are an authoritative source of information about the conduits, having been investigating them for 25 years.

148. Good conservation of heritage assets is founded on appropriate routine management and maintenance. Such an approach will minimise the need for larger repairs or other interventions and will usually represent the most economical way of sustaining an asset.

Furthermore the RPA's own document TRP Corporate Plan 2009-11 contains the following clauses:

"We value the historic landscapes and buildings which we hold in trust for the nation"

"To conserve and [sic] the historic built environment of the Royal Parks"

Looking at the condition of some of the conduits in the park, there would seem to be scant evidence that these lofty aims are being achieved.

Failure by the Royal Parks to implement these key directives would amount to a rejection by them of some of the most fundamental parts of PPS5 as well as the TRP Corporate Plan.

¹ There is a brief account of the lower section of the Hyde Vale Conduit on the EH/NMR web site PastScape, along with general references to two other park conduits - those near Queen Elizabeth's Oak and one at One Tree Hill.

Cemetery Mine, Plumstead

No comprehensive survey of the Cemetery Mine is known to exist; its general location was in the area of Rockcliffe Gardens, site of numerous ground collapses...

↑ Click for a larger version (617k 722 x 1000)

Small pieces of the mine were revealed by test headings dug underground by Legrand, Sutcliff and Gell (who incidentally also sank the new shaft that re-opened the Blackheath Cavern). The gardens were created in the 1950s after it was decided that this area of land was too dangerous to build on, although in 1987 a developer acquired the land with an intention to place a substantial housing development (Prestwood Close and Radnor Crescent) on this highly unstable piece of ground - a very unwise idea. The ensuing campaign by local people against the developer, under the guidance of Per von Scheibner, became known as the "Battle of Alliance Road", and featured extensive weekly coverage in local newspapers. The developer was ultimately forced to carry out a tight 1 metre borehole grid across the whole site during 1988, which revealed dozens of large voids - proving the existence both of large air pockets from collapsed galleries heading upwards as well as lost intact galleries. Extensive (and expensive) remedial work was carried out to stabilise the ground.

The residents of these new streets are now safe; however, outside the perimeter of the development, further voids and unsurveyed passageway probably still exist.

↑ Rockcliffe Gardens, showing mine features and collapse areas. Click for a large version (306k 1600 x 1126)

↑ The area of Rockcliffe Gardens, with voids ("V") discovered during borehole drilling in 1988; many more voids were subsequently discovered. Click for a large version (172k 1248 x 720)