St George's Day was marked by a dragon parade to highlight links between Shakespeare and a town's theatre.
University of East Anglia researchers found the playwright performed at King's Lynn's St George's Guildhall in 1592.
He was also born on St George's Day in 1564 and died the same day in 1616.
Snap the Dragon led the parade, visiting for the first time since 1546, to launch a £100,000 campaign to renovate the theatre, organisers said.
To launch the appeal, a lunch was put on at which Royal Shakespeare Company actor and British Shakespeare Association board member Tim FitzHigham read a passage from Shakespeare's Henry V.
In the play, the character of the king called his men to battle with the speech: "I see you stand like greyhounds in the slips, straining upon the start.
"The game's afoot: Follow your spirit, and upon this charge cry God for Harry, England, and Saint George!"
The Shakespeare's Guildhall Trust, which organised the lunch, is campaigning to retain the building as a mixed arts venue.
As campaign funds come in over the next 12 months, the Guildhall, which is currently mainly in use as a cinema with occasional stage performances, will be renovated for all performance arts, the Trust said.
The building is owned by the National Trust, but leased to the borough council.
Built in 1410, its first recorded use as a theatre was in 1444, and it is believed to be England's oldest theatre still in use for staged productions.