archaeological & built heritage assessment - The Heritage Council

Area 3
Area 3 has been defined as that comprising the Boyle River, Lough Key, including Knockvicar and Boyle (Clarendon
lock, Knockvicar bridge, Drum bridge, Rockingham park)
The stretch of water from the junction with the Shannon up to Lough Key is one of the most attractive
on the waterways navigation. It is a series of lakes connected by short stretches of river. It was used from
early times by small trading boats until the Shannon Commissioners deepened the channel in a few places
and constructed one lock to make it fully navigable into Lough Key and up the Boyle River to within a
short distance of Boyle (Delaney 2000). Once through Oakport lake, a quiet amenity area, the Boyle river
becomes much narrower and winds its way towards Knockvicar.
Knockvicar bridge is of the same design as Cootehall; here, too, it was recommended moving the site of
the bridge downstream a short distance to permit realigning a new road but, as at Cootehall, the cheaper
option of erecting a new bridge on the old site was adopted. There was a mill on the west side of the
bridge in existence at this time and the old millrace can be traced in the grounds of the mill-house above
the bridge (Delaney 1987).
The stretch of river from the bridge to Clarendon lock is also a very scenic area within the waterways
corridor. Here the Commissioners constructed a lock, naming it after the Lord Lieutenant of the time,
and beside the lock they built an open weir. New gates were installed in 1958 and a new quay stretches
up towards Lough Key (ibid.).
Within Area 3 there are a number of country houses including Errironagh House, Riversdale House and
Rockingham demesne. The latter is administered by the Forest and Wildlife Service as a forest park.
Rockingham house was badly damaged by fire in 1957 and the entire estate was bought by the
government two years later to become one of Ireland’s first forest parks. Rockingham house dominated
the lake as one turned into the bay and approached the shore. Today, a structure called the Moylurg
Tower occupies the site where the house once stood.
This area was MacDermot territory right through from the twelfth to the seventeenth century and there
was a settlement on the shores of the lake with a fortress on the nearby island, known as The Rock,
which is now called Castle Island. The Annals of Loch Cé, which commence in 1014 and end in 1590,
chronicle the history of the MacDermot family and the many battles which were waged around The Rock.
In 1578, when times had become slightly less turbulent, it is recorded: “The great regal house of the Rock
was begun by Brian, the son of Ruaridhri MacDiarmada, and he had this work and the head [roof] of the
monastery of the Trinity, and the bawn of Dungas, in progress together”; the latter is thought to have been a
house on the mainland where the Moylurg Tower now stands (ibid.).
The MacDermot lordship of the area was soon to decline and their lands were granted to Sir John King in
the seventeenth century who proceeded to built and shape Rockingham house and estate throughout the
next century.
Lough Key is an interesting lake with several small islands and extensive archaeological remains of
medieval date. On MacDermot’s Rock (Castle Island), during the eighteenth century, Lord Lorton built a
type of folly castle using parts of the old castle which were still standing. Francis Grose included a drawing
of the Rock made in 1792 in his Antiquities of Ireland which gives an impression of how it looked before
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