Northampton Borough Council was warned to add emergency strapping to the crumbling Eleanor Cross monument in November but did not do so, a hidden report has revealed.
In recent years the historic monument in London Road has fallen into disrepair with both the borough and county councils claiming it was not their responsibility to repair.
The stalemate seemed to have reached a conclusion last year when the borough took on responsibility for repairing the 13th-century structure.
The authority commisioned Cliveden Conservation to "winterproof" the 700-year-old cross last October by carrying out minor repair work.
But the cabinet meeting at Northampton Borough Council on Wednesday night heard how experts had advised the council to carry out emergency structural repairs as far back as November.
An independent report by the company Clarendon, the meeting heard, advised "strapping" be added to the cross as it was at risk of collapse. The details of the report only came to light after a Freedom of Information request by a member of the public.
Historians now fear the listing 13th-century monument, one of three remaining in the UK, will "fall to pieces" after finding new cracks in the stonework.
Speaking at the cabinet meeting on Wednesday, Councillor Julie Davenport (Independent, Delapre and Far Cotton) questioned why the council didn't act on the report in November.
She said: "Unknown to everyone, Northampton Borough Council carried out a survey in November.
"Clarendon said it needed work doing to do it immediately and needed immediate strapping done to it.
"However, this work was never carried out.
"If you did not take the remedial work required by that report there must be a reason. We need to know.
"Now it can be called the leaning tower of Delapre."
Northampton Borough Council says it aims to begin work on the cross by autumn and is seeking funding from Historic England to do so.
The cross, situated at the southern end of London Road close to Delapré Wood, was commissioned by Edward I between 1291 and 1294.
Each of the original twelve monuments marks one of the nightly resting places of his wife, Queen Eleanor of Castile’s, funeral procession between Harby, near Lincoln, to London.
Councillor Davenport says that money must now be found to carry out the emergency work.
"I have had so many residents contact me," she said.
"They can't understand that for Abington Museum they can find millions, but unless an Historic England grant can be found the work to the Eleanor Cross can't be done."
Responding at the cabinet meeting, leader of the council, Councillor Jonathan Nunn, said: "I don't think the cross is leaning like you say.
"I don't think there is subsidence.
"Ther is some suggestion of cabinet member involvement or skullduggery of some sort.
"That is not the case. Historic England has had to approve everything that happens.
"You can't do anything without their step-by-step approval."
Regeneration consultant at the council, Rick O' Farrell, told the meeting that he was not sure why the report was not acted upon at the time. He only assumed the regeneration role in January.
However, he said the strapping work will be carried out ahead of the full restoration programme in autumn.