View this artwork by appointment, at Tate Britain's Prints and Drawings Rooms
As Finberg thought, this sketch seems to show the interior of one of the glass-roofed conservatories at East Cowes Castle;1 it is likely the smaller of the two (at 9 by 12 metres, some 30 by 40 feet), which opened off the drawing room at the western corner of the house. At the other end, its south-western façade comprised three round-headed arches, which feature in many exterior views such as Tate D20830 (Turner Bequest CCXXVII a 27). Its longer north-western side was a wall, and its corresponding south-eastern front a glass arcade.2
Turner appears to be looking westwards, with the three arches on the left and the blank wall to the right. At each side elegant women are shown; echoing the pose of the one on the left, the most prominent feature is a classical statue of a woman, possibly a water-carrier, set high on a plinth within a trellis arch, while in the foreground is a free-standing ornament, perhaps a fountain or basin supported by birds. Compare the outdoor statue and pool in D20840 and D20841 (CCXXVII a 37, 38).
This is among dozens of blue paper studies made in and around East Cowes Castle, presumably during the same visit. For more on the various aspects of the house (demolished in about 1950), and its lost grounds as depicted by Turner, see the Introduction to this subsection, where other views of the interior are noted.