Legends & Mysteries 

Fort Purbrook - Tunnel No1

 Created 15-07-2002    Last update 08-08-2003

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Crookhorn Redoubt - Tunnel No1

Crookhorn was to have had Caponiers, counterscarp and scarp galleries and its own magazine and barracks. Unfortunately the fort was sited half on a stratum of blue slipper clay, and in order to reduce costs the northern half was abandoned leaving the remainder as just a prepared earthwork. It could have had little value and is shown as demolished in the armament returns of 1876.

The plans for Crookhorn Redoubt show that it was to be linked to Fort Purbrook by a tunnel. The Solent Papers No 3 first published 1987 by Gary Mitchell state:  there is evidence for this [a tunnel] in the Musketry Gallery at the end of the double Caponier at the north east salient of Fort Purbrook. 

Plan of Fort purbrook

Lower plan of Fort Purbrook. 

'A' is the Musketry Gallery in the double Caponier of the north east salient, where evidence of a tunnel to Crookhorn Redoubt was said to exist.

Copyright David Moore - Palmerston Forts Society

Fort purbrook north east Caponier plan

Original plan of the northeast Caponier (marked 'C') and the Musketry Gallery (marked 'M) of Fort Purbrook. Notice the hatched lines leading away northwards from the Musketry Gallery.

Copyright David Moore - Palmerston Forts Society

Crookhorn Redoubt plan

Lower plan of Crookhorn Redoubt.

On the bottom left of the plan is the tantalising legend "Tunnel to Fort Purbrook".

Copyright David Moore - Palmerston Forts Society


On 24 July 2002 as part of a visit to Fort Purbrook organised by the Palmerston Forts Society, I made my way to this part of the Fort along with Peter Cobb from the UK Fortifications Club. The idea was to see exactly what the 'evidence', as recorded in the Solent Papers No3, consisted of. We were pretty surprised when we got there.

Fort Purbrook portal

At the end of the Musketry Gallery of the north east Double Caponier is a bricked-up section of  much later origin than the surrounding Victorian brickwork.  At some time in the last five years - since the last visit by  Peter Cobb - a hole has been knocked through this revealing some boarding-up behind it. Interestingly there is no sign of Doorpost or Lintel - the "blind wall" concept. Was this tunnel walled-up during construction and only to be broken down in desperate circumstances?


The more modern brickwork was obviously the 'evidence' referred to in the Solent Papers No 3, and is thought to have been put there sometime during the second world war or later. The brick-laying was done with care, and has been bonded into what was the Victorian opening.  It was just possible to photograph what was behind the upper right portion of the boarding-up.

The Fort Purbrook to Crookhorn Redoubt tunnel

It was just possible to photograph through a gap in the top right of the boarding: a tunnel - or at least the roof of one. It is only around 5 feet in height, and backfilled with chalk to within 9 inches of the roof. The top of the tunnel is 2 feet 6 inches wide, but increases in width - maybe up to 3 feet - at the base. It was only possible to see back 10 feet. The narrowness of this portal suggests that it was a 'pinch point' allowing it to be defended with comparative ease. It probably opens out into a larger tunnel a little further back, along which fully armed troops could move.

Tunnels around Fort Purbrook

An aerial photo showing the positions of the two known tunnels emerging from Fort Purbrook. No 1 tunnel is awaiting further investigation.. No 2 tunnel is described here. The location of the suspected tunnel to Farlington Redoubt, located on the right, is still unknown but I suspect that it tees-off from tunnel No 1.

Fort Purbrook was one of the few Forts to be fitted with Chicanes in the tunnels below the parade ground. One such equipped tunnel is the one leading to the north east Caponier described above. [a chicane in this sense is used to describe a deep pit in the tunnel covered by a drawbridge. If the enemy get into the Caponier then the drawbridge can be raised leaving both pit and barrier as a defence]. It could be said that the reason chicanes were used in this instance was because of the vulnerability that the Crookhorn / Purbrook tunnel presented. If the enemy took Crookhorn Redoubt then there was a direct route into Fort Purbrook. The only other forts that I know of that were fitted with Chicanes because of their vulnerability were Grain Fort and Detached Bastion Western Heights. One other thing. It is my belief that if a Fort Purbrook / Farlington Redoubt tunnel exists then it will be found as a tee junction in the Crookhorn tunnel.  In support of this theory here is an extract from the Illustrated Times of 26 September 1863. For the term 'sunken gallery' read tunnel: 

At the east end of the hill the works are the least forward of any, but here may be seen the unusually formidable nature of the trace.  It is commanded by three works Farlington, Crookhorn, and Purbrook. All three have yet proceeded in their construction but little beyond their formation of parapet and ditch and general outline. Their height reaches -300ft. above Ordnance level. Farlington commands the eastern point of Portsdown, and will mount eighteen of the heaviest guns on its terre-plein, with mortar-batteries in the angles of its surrounding ditches, each battery mounting three mortars. A sunken gallery communicates with Crookhorn, which will mount sixteen guns on its terre-plein, with six guns in the angles of its ditch. A continuation of the same sunken gallery leads from Crookhorn to the main work at this eastern end of Portsdown -Purbrook which will mount twenty-one guns on its terre-plein, nine guns in caponieres in the ditch, and three mortars in the ditch‘s west angle. It has a nearly straight face of 240ft., looking inland; the open gorge being opposite the west side of Langstone Harbour. The ditches surrounding the three works vary in depth according to their position from 35ft. to 50ft. Sunken galleries from the interior of the works communicate with the mortar batteries and caponieres in the ditches.

It certainly looks as if the legendary tunnel connecting Fort Purbrook to Crookhorn Redoubt is no longer a legend, but it still remains a mystery as there are un-answered questions remaining such as: how long is it? Is there any archaeology in there? Does it continue in the right direction? In response to this I am currently attempting to get permission from English Heritage to investigate further.


*** Latest News ***

On 8 August 2003 I met at the fort: Rob Perrin from English Heritage and Jenny from Portsmouth Museums and Records Service. We had a meeting to discuss ideas about how the tunnel could be further investigated and after inspecting the portal it was suggested by me that the best thing to do was to remove 1 or 2 bricks in the wall at tunnel roof level so that a visual inspection could be made to determine just how extensive the tunnel and the backfill was. Rob Perrin was very agreeable to this since it meant that only the post-Victorian brickwork would be disturbed and because it raised no health and safety concerns. Likewise Jenny thought this 'minimum use of force'  idea made sense and said that she would contact the relevant departments in Portsmouth City Council to verify that this course of action would be acceptable to the forts owners.


During this last visit I managed to squeeze a camera through the gap between the wall and the boarding-up and take some photos using infra-red for illumination. Here are the results:


above the spoil heap

View above the back-fill. Notice that there seems to be an edge to the right-hand tunnel wall about 12 feet back from the portal.

close up

A close-up shows the edge more clearly.

enhanced photo

This enhanced photo of the above shot seems to indicate that the tunnel takes a right-hand turn. This would correspond exactly to the layout of the Crookhorn end of the tunnel in the plans above. Other possibilities are a dead-end (but then why bother back-filling the entrance?) or water vapour. The back-fill is casting a shadow indicating that it ends here.


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