The partial bowl of the clay pipe was found at a depth of 550mm by the wall, which looks to date from the first half of the 1800s.
Archaeologist Jann Beresford from Wessex Archaeology conducted a search of local pipe makers from census documents to dig up possibilities for the pipe’s origins.
Jann said: “It’s likely that the pipe was made by John or Joshua Goodall at Fareham Pipe Makers between 1841 and 1851.
“Back then, pipes rarely travelled further than 15 miles from their makers because they were usually considered disposable. They were sold filled with tobacco and discarded after use.
“This is an exciting local find, and it’s amazing to see that the leaf design on the pipe bowl has remained remarkably intact over the years.”
The pipe is the second artefact found during the works. The first was a copper bell found under Castle Field earlier this year.
Guy Mason, Southsea Coastal Scheme Project Director said: “We continue to work closely with Wessex Archaeology and have an on-site archaeologist present throughout our works.
“This has been particularly important on the first two frontages of the Southsea Coastal Scheme as our construction sites at Southsea Castle and Long Curtain Moat have strong historic significance.”
Portsmouth City Council, Wessex Archaeology and Historic England maintain regular contact to agree appropriate recording strategies as remains are uncovered. This is in line with the project’s Historic Environment Mitigation Strategy, as well as planning conditions and Scheduled Monument Consent.