Oops - my mistake - it fell for the first time in 1834. At present two of the uprights are stacked on top of the capstone with another underneath it. The capstone is 3.3m x 2.5m x 0.3m. The top two uprights are 2.7m long.

The following extract may be of interest - I've put the drawings from Dr William Borlase' book Antiquities of Cornwall published in 1754 in the images section for this site.

NAENIA CORNUBIAE
The Cromlechs and Tumuli of Cornwall
William Copeland Borlase
1872

CAERWYNEN CROMLECH. After this digression it remains to glance at the one other instance of a "Cromlech proper" which Cornwall affords; before passing on to the more extensive subject of the Kist Vaens. This monument is situated in the centre of a sloping meadow on a tenement called Caerwynen, immediately opposite the front windows of the old family mansion of Pendarves. Similar to Lanyon Cromlech in its construction, it has also shared its fate, for it fell many years since; but was, as a labourer asserted who had assisted in the work, soon after replaced by the patriotic lady of the manor, in much the same position as before. Fortunately a drawing of it by Borlase, (larger than that in his published work) is extant in his MS. collections, from which the accompanying, engravings are taken.

The two supporters at the south-eastern end seem to have retained their original positions. They were formerly, respectively 5 feet 1 inch, and 5 feet 2 inches above ground, and are still nearly the-same height. The single pillar at the other side has been moved nearer the edge of the covering stone than in the above sketch; it measured 4 feet 11 inches high, but is now shorter. The covering slab, which, like the other stones, is granite, measures twelve feet by nine; one side, however, seems to have been broken in its fall. Some stones now standing on the north side, were placed there subsequently to the restoration. No pit was sunk beneath it, nor has it ever been explored, and there are no remains of a tumulus under or around it If explored, (which would be in its present state a dangerous operation), it is highly probable that a grave similar to that at Lanyon would be found, the area between the supporters being formerly seven feet long by about five broad though now something more.