Not all that easy to locate, having tries a few times over the years. Several weeks ago it was finally spotted here in FS2004:

Locating Stonehenge (in most MSFS editions since FS4, though MS apparently spaced getting it into FS8):
N51 11.13 W1 50.95 from EGDM, Boscombe Down.
Vector 302° to 303° for just over 4 nautical miles. With careful eyes you'll see it.
Not easy to find but rather rewarding when you do, shown here with medium overcast skies,
flying Rick Piper's amazing Hawker Siddeley twin Rolls-Royce Dart turbopropped HS.780 Andover C1.
.