The historic pub has been closed since November 2013 after Wetherspoons bought the Grade II listed building.
The chain had plans to redevelop the pub, which were approved in February 2015 and included blocking the passageway which gives access between High Street and Church Street.
But by this time campaigner Darren Woodward had submitted an application to ensure the passageway was designated a public bridleway.
He applied to add the bridleway to the Definitive Map and Statement for the town on the grounds that is subsists or was reasonably alleged to subsist, having been a way used both on foot and for bikes.
Campaigners then had to prove the passageway had been used without interruption by the public for at least 20 years before Wetherspoons fenced it off in 2013.
Historic documents on the pub, seat of the Great Fire in the town in 1785, failed to show an official public right of way although the documents at Bedfordshire and Luton Srchives did show the route had been available for many years.
Biggleswade History Society interviewed 51 residents who said they had regularly used the passageway in the past 20 years and more people contacted Central Beds Council to confirm their regular use of the site.
A consultation was then carried out involving Biggleswade Town Council and local groups but Wetherspoons then expressed their “disappointment” at the investigation and queried much of the evidence.
After the pub chain appointed Counsel to query the findings, Central Beds Council then sought its own Counsel’s opinion who found that the evidence supported the move to make it a public right of way.
At the council’s development Control Committee meeting last week, members hear the council now has a duty to deem it a right of way.
Jane Croot, for the History Society, told the meeting: “A lot of elderly people use it and it allows a safe use for the schools. I’m glad that Counsel has deemed it a public right of way”.
But Cllr Ken Janes condemned the move saying the placing of the road crossing further down High Street showed it was not a direct route and to use it as such could be dangerous.
And Cllrs Steve Dixon and Frank Firth said they had always used it with a sense of guilt, not being sure if it was a public right of way.
After approving the motion that the passageway would be included as a public right of way, Chairman Cllr Ken Matthews said the onus was now back on Wetherspoons to change their plans.