There are some clues -
The present day names of the fields next to the circle field to the south west and south are 'Top Castles' and 'Bottom Castles'.
According to Pennant ref 1 in 1772 the name of the Circle field itself was 'Castle'
According to several 19th century books the name of the lane from the Druid Circle to the Ambleside road was "Castle Lonnin" as it is in the vernacular to this day.
However these names might be referring either to the stone circle itself as a 'castle' or to the Roman fort which we now know was adjacent to the stone circle.
Also, the lonnin runs both ways and the castle may well have been at its other extremity as indicated by both Green and Rawnsley (below)
Some old maps, most notably Ogilby's map of 1675, record a place called 'Cust' adjacent to the old Ambleside road south of Keswick. It is conjectured that this 'Cust' is a mis-copy from an earlier map of 'Cast.' meaning castle. (Many of these old maps were copied one from another)
Ogilby's map is quite accurate in terms of distance measured along the road with markings every quarter mile.
His map shows 'Cust' as being a mile and three furlongs along the Ambleside road from its junction with the Borrowdale road i.e. from Keswick Market Square.
A difficulty remains - it is believed that the old road followed a steeper, more direct route over Castlerigg than the present road but its exact course it not known - and, particularly on the Keswick side of Castlerigg, is not easily conjectured. However it must have passed close to Castlerigg farm.
[p5]
The ancient castle, or family seat of De Derwentwater is
supposed to have been situated on the top of the ridge above,
and south-east of the village of Castlerigg.
[p
462]
Druids Temple
These stones are situate at the top of the hill, one mile and
three-quarters on the road from Keswick to Penrith, and
perhaps, one hundred yards from that and the cross road leading
to the ancient Castle on Castlerigg.
[p
464]
The Castle on Castlerigg
The nearest way to the place where this castle is supposed to
have stood, is on the Ambleside road one mile; thence on the
Ambleside road through the village of Castlerigg; but that from
the Druids Temple is on the highest ground about three-quarters
of a mile, and there crossing the Ambleside road it leaves the
Nest a little on the left; at the end of of about half a mile
more it joins the ancient road by Castlerigg, just mentioned,
from which it is a few hundred yards to the union of the old
and new roads near the second milestone from Keswick.
Descending towards this junction in the southern corner of the
first field on the right, are the foundations said to be those
where anciently stood the castle of the family of De
Derwentwater, but if these paltry stones were those on which
their fabric was erected it could not have been of great
importance. Its situation, however, on the side of a rocky
declivity while receiving the morning and noon-tide sun
protected it from the northern tempest; and commanding views of
craggy elevations beyond the beautiful valley at its foot, was
fitted by nature as the seat of opulence and power, and, when
fortified, as a secure retreat from marauding depredators.
{OS grid ref: NY28762215
or 54.5895833N,3.103889W}
See footnote
[p 61] "......From this place {Druid Circle} the reader may proceed, by way of Castle Lonning, to the Ambleside road. The view from the brow of Castlerigg, on the return towards Keswick, is said to be unequalled in England in point of richness, variety and beauty. Gray ref7, it will be seen, was enchanted with it, so that he "had almost a mind to have gone back again."
A modern tourist has finely sketched this scene in verse, { verses omitted}
As a pendant to our present excursion may suitably be included the ascent of Wallow Crag, the approach to which it will be seen strikes off here by way of Castlerigg farmhouses to Rakefoot
The last traces of the castle of the Derwentwater family, which stood in a field to the left of this road, and which was abandoned as a family residence on the marriage of Margaret*, heiress and representative , to Sir Nicholas Ratcliffe of Dilston**, disappeared before agricultural improvement only a few years ago."
* The heiress appears to have been called both Elizabeth and Margaret.
** Not correct, the Radclyffes of Derwentwater did not acquire Dilston Hall until two generations later. ref 4
"Up Castriggs naked steep - we, with Wordsworth's
waggoner, now make our way. But the commons enclosure has
robbed it of much of its nakedness. Upon our left is seen one
of the ancient milking rings - a circular fence of holly trees.
We pass along slowly as the horses feel the hill. It is a grand
view that we now have of Helvellyn, if we will but look
backwards.
{...} and just as we pass Pyats Nest of last century - the High
Nest of our day - we note, far to the east, a cluster of houses
in the plain - 'and see beyond that hamlet small / the ruined
towers of Threlkeld Hall'
{...} As one looks upon Blencathra with its triple breast and
strange saddle buttress— alternate gloom and glory to-day
from the swift chase of sun and shade. — one feels something
of the weight of mystery laid upon one's spirit that dictated
the choice of site to the Druid worshippers of old time. We are
at Castle Lonning end To the left runs the old Penrith
road to the camp or castle, to the right runs the lane to the
Druid circle, unique with its thirty-eight stones in outer
circle and its eastern inner sanctuary. It is a thousand pities
our coach-road just misses sight of this circle."
"....The original residence of the Derwentwaters was situated in the vicinity of Castle Lonnin, on the high ground at Castlerig, to the east of Keswick, but the remains of it have disappeared."
By visual inspection the most promising location would
appear to be in what is now a wood 100 yards west of the Castle
Lonnin road end adjacent to the highest point of the A591.
{NY28672271 or 54.594583N, 3.105417W}
Summary
Options 1 can be discounted, The stone circle is too isolated in the middle of what was then a Common - any Manor would have had its demesne lands around it
The other options all agree the location is to the south west of the present day main road i.e. towards Rakefoot and Castlerigg farms, furthermore, they agree that it was near one or other of the ancient roads.
Options 2 and 4 agree on a location near the old main road near Castlerigg Farm
Options 3, 5, 6 and 7 place it further south or east, option 3 (and maybe 5) further south along the old main road and the remainder near the old drove road which extends Castle lonnin to the old main road
References
ref 1 A Tour in Scotland and Voyage to the Hebrides, Thomas Pennant.1772 p43
ref 2 The tourists new guide Vol. 2 by William Green 1819 p 464
ref 3 Keswick and its Neighbourhood 1852
ref 4 The Gentleman's Magazine Vol. XXXI 1849 p 471
ref 5 Trans CWAAS Part 1., Vol XII, Art. XIV.—
Some Manorial Halls in the Vale of Derwent By Michael W.
Taylor, M.D., F.S.A.
(Download
- 17MB pdf)
ref 6 A Coach Drive at the Lakes,
Windermere to Keswick
By Hardwicke Drummond Rawnsley, Edition: 2
Published by T. Bakewell, 1891 pp76-79
ref 7 Thomas Gray, Journal in the Lakes 1769
'Cust' as shown on Ogilby's map of 1675
About the map
The name 'Cartherit a Vill.' is as puzzling as 'Cust'. Elsewhere on the map Vill. is an abbreviation of village. Cartherit may be a variation of Castlerigg or even Castlet which was an old name for Castlehead. Ogilby seems to have had cloth ears when people told him the names of places - for example he labels Smeathwaite bridge as 'Smathods' brig.
A reworking of Ogilby's map by Jeffries in 1775 changes 'Cartherit' to 'Brow Top' which is probably correct, Brow Top is the right distance along the road from Keswick Market Square and the line of this road is quite direct and probably unchanged since the earliest times.
Jeffries attempts to rationalise 'Cust' as 'Cust
Way Foot', identifying it with the present day Causeway
Foot. This is unconvincing.
The distance from Brow-Top to Causeway Foot is 1.45 miles as
the crow flies and nearer two miles by road whereas Ogilby's map
shows Cust as being just under three quarters of a mile
along the road from 'Cartherit' / Brow-Top.
Jeffries map is more colourful than Ogilby's and removes the scroll -effect curvature and shading. However it is less accurate in terms of distances (no quarter mile marks) and introduces its own naming errors (e.g. 'Burden' for Borrowdale, 'Royal Mines' and Fornside in the wrong place, 'Thralkeld' is placed at Stanah, Roughhow Bridge over Naddle Beck is labelled 'Smathods Bridge over Thurlmire R.')
It now seems that the ruins Green describes in option 3, above, are those of the old farmstead of Causeway Head. Some artefacts from Causeway Head are in the Cumbria Archives at Whitehave. Causayhead or Kasyhead is mentioned in 13 places in The Registers of Crosthwaite (1600-1660) .