The two wellheads and other fragments are thought to date from around 1805, the period following James Wyatt's Gothic restoration and extension of the original Palace of Westminster, ordered by George III.
How they came to reside in a garden in Guildford is unknown, but they would have been removed from the building following the disastrous fire of October 16, 1834, which broke out directly under the Lords Chamber, burned through the night and reduced the central area to ruins.
Sir Charles Barry won the open competition to design the replacement.
It is known that prominent political figures of the day, including Sir Robert Peel, were given the unwanted statues and architectural fixtures from the ruined building, but all Ewbank's vendor can say is that she remembered them from her childhood, 50 or 60 years ago.
The Westminster provenance of the pieces is plain to see. A weathered hexagonal wellhead is carved with alternating shields, of lion rampant and three lions passant, all topped with a crown. With its later decorative wrought iron, the piece stands almost 8ft (2.4m) tall and is estimated at £3000-5000.
The same estimate is given to another larger wellhead carved with repeating Gothic arches and crowns, while a pair of carved stone bases pierced with quatrefoils is estimated at £1500-2000.
The stonework has been removed to Ewbank's Burnt Common auction rooms in Send and will be offered for sale on December 18.
By Roland Arkell