A regional daily has won a fight to reveal details of a secret report into an £18bn plan for its patch – but faces an ongoing battle to make further information public.

Bristol Post local democracy reporter Adam Postans has successfully pressured the West of England Combined Authority into publishing some financial details about the construction of a potential underground rail network in the city.

WECA has agreed to publish the findings from the report that focus on finance but has decided to keep the rest of the 248-page feasibility study under wraps.

The Post has now appealed to the Information Commissioner’s Office against WECA’s decision to refuse Adam’s Freedom of Information request to release it – a decision upheld by the combined authority after the Post asked for an internal review.

The Post splashed on the story on Thursday (27)

In a piece about the FoI battle, Adam wrote: “We have argued that the full document should be published in the public interest and that the elected head of WECA, Labour metro mayor Dan Norris, has said he has no problem with that.

“But officers in legal and democratic services have determined that the report by consultants WSP should not be released for now because it is still in draft form and based on incomplete data, so could ‘prejudice future decision-making and debate’ and create a ‘misleading impression of the work being carried out’.

“This is despite us having already obtained and widely reported its conclusions that say an underground for the West of England would cost between £15.5bn and £18.3bn, while an overground network would set taxpayers back about 10 times less – £1.5bn to £1.8bn.”

Post editor Pete Gavan wrote on Twitter: “Getting this into the public domain was down to great work by Adam Postans asking the right questions and pursuing the story when told ‘no’. Another illustration of the importance of the stories the LDRs produce day in, day out.”