The Keep, Tregantle Fort, Antony, Cornwall

In March and April 2007 Oxford Archaeology carried out a programme of historic building
recording and investigation on the Keep and SW, NW and NE caponiers of Tregantle Fort,
Antony, Cornwall on behalf of the Defence Estates. The purpose of the survey was to record
the current state of the Keep and caponiers and increase the understanding of the buildings.
Tregantle was one of only three known Palmerston Forts to have had a purpose built Keep. A
detailed record of features and fixtures of the Keep was also produced with the aim of helping
to produce replicas in the weather proofing works and securing the Keep’s historic integrity
within its long term preservation.
Tregantle was constructed between 1859 and 1864 and it was intended to be one of three
forts on the Antony line defending the western side of Plymouth Dockyard. Only two of these
forts were constructed, the other one being Scraesdon. The fort was intended to be armed
with 87 guns but it appears that a relatively small proportion of these were actually fitted. By
1895 it is known that six 64 pdr rifled muzzle-loading guns had been installed in the Keep,
five of which were on the roof and the other is thought to have been fitted in Room 16A to
cover the drawbridge. In 1903 the Fort became an infantry battalion headquarters and in the
Second World War it was used by the US Army.
Although the condition of the Keep’s main structure (stone walls and barrel vaulting) is good
the timber elements (suspended joist floors and joinery) have suffered considerably from
damp and prolonged disuse. However, examples do survive of most of the main internal
features such as doors, windows, panelling, fireplaces etc so that a reasonable understanding
can be gained of the Keep’s historic form and it should be possible to reconstruct good
replicas of these items.
Although some of features or elements are clearly secondary (breeze block infilling
embrasures, some brick walls, plant from electrical generator room) the large majority of the
surviving joinery is believed to be essentially primary. This does not necessarily mean that it
was all installed in a single phase in the 1860s when the fort was completed. By the time
many Palmerston Forts were completed they had become partly obsolete and they were no
longer required for their intended function. This is why the majority of the guns were not
fitted at Tregantle and it may be that it took many years for the Keep to be fitted out as there
was no longer an urgency to complete it. There is some evidence to suggest that the eastern
half was fitted out later than the western half (painted ceilings beneath former partition lines)
but this does not necessarily mean that these partitions replaced a previous arrangement.
The curved western half of the Keep appears to retain much of its original basic layout and it
has undergone much less alteration than the two ranges in the eastern half. The layout of
almost all the rooms to this side have undergone changes, the principal phase of which
appears to have been undertaken in the early 20th century when the fort became an batallion headquarters and the Keep became mainly used for storage. At this time several brick walls
were inserted to alter the plan and the partitions which are believed to have flanked the
central corridor (much like the western half) were largely removed. However there does also
appear to have been a further phase after the original construction of the Keep but before it
was being largely used for storage. During this phase, in the late 19th and very early 20th
centuries, several of the plain primary fireplaces appear to have been replaced by slightly
more elaborate ones possibly reflecting a use with a higher status (eg Officers
accommodation). These fireplaces are distinctly different to the original ones and must represent a second phase although it may have been shortlived before the Keep was given
over to storage.
The investigation of the caponiers has identified the two mounts a 32pdr Single Bore Breech
Loading (SBBL) gun which was tested in a series of trials between 1885 and 1892. These
mounts are in the lower tier of the double caponier