Thanks VBB for your informed post .. I have just had a quick look in Rosemary Hill's very readable book on Stonehenge and there are some reproductions of pre (and early) 20th century images:

"Turner's watercolour view, engraved by Robert Wallis,1829. The shepherd lies dead in the storm, the sheep abandoned. For the Romatics the stones were predominantly a place of psychic dread and terror" This image shows a ruined Stonehenge. (Chapter 4)

There is also a photograph of about 1896 showing the fallen western trilithon and the timber supports propping the leaning stones.

Roy, am glad you enjoyed the Silbury bit. Jim Leary certainly mentioned the Winterbourne/Kennet rivers and Swallowhead Spring as being a source of the Thames in the talk he gave prior to the book being published. The Thames of course has more than one source - the highest being in Gloucestershire. Its a another theory and as good as any ... I like it.