Plans to extend Berkhamsted town centre by creating a new piazza and walkways between its High Street and Butts Meadow Recreation Ground have come under scrutiny.
Thirty professionals working unpaid for the community group B-Hive drew up the recommendations in a 95-page report.
They are based on the results of a town consultation, where people said what they would like to see developed around the town’s central High Street sites.
B-Hive spokesmen Hugo Hardy and John Bell told Berkhamsted Town Council on Monday that their plans would increase frontage space for shops and offices by 500 per cent.
But the meeting heard that the bidding period for the empty police station site has now closed.
B-Hive’s vision is that the property should be opened up for use by the public and small businesses.
But councillor Laurence Handy said if its buyer does not want this to happen, then the B-Hive proposals could be scuppered.
Mayor Ian Reay said without a developer to take the plans forward, they would be just ‘lying there’.
A development brief for the other side of the High Street was developed by Dacorum Borough Council six years ago but nothing was done with it, he said.
Others criticised the lack of clarity about how much the plan would cost to implement.
Councillor Tom Ritchie said: “Are we talking about £5m in 10 years, a £100m in five years? I have just got no idea. Before we go too far with a plan, don’t we need to cost this?”
Councillor Elaine Collins said: “When someone comes here and says they have done sums on the back of an envelope and we are talking about a multimillion-pound project, I do not think that’s acceptable.”
She said the public should have been asked not just how they would like to see the town develop, but what they would be prepared to pay for.
But, standing up for the project, councillor Danny Bonnett said the report was drawn up in three months by people working in their spare time.
Councillor Garrick Stevens said: “This is the embryo of what could be a masterplan for this part of the town centre. I do not think we should give up on it.”
Mr Reay said he would ask Dacorum Borough Council to talk to B-Hive about their 95-page development brief.