A Westcountry council is facing a choice between paying out a massive compensation bill – or allowing a new supermarket to be built which could damage town centre trade.
West Devon Borough Council has been left with the dilemma after a legal challenge hit the buffers at London's High Court.
They can either fork out an estimated £500,000 in compensation by formally revoking the planning consent that the council granted by mistake.
Or they can leave the planning consent – which paved the way for a supermarket to move on to a retail park in Tavistock – as it is, even though they say such a supermarket is not needed in the town and as it would hit the town's retail trade.
The council is barred by law from the cheaper option of challenging its own decision in the High Court.
But, in a bid to still have the council's mistake judicially reviewed by one of the country's top judges, council leader Philip Sanders launched a personal action seeking permission to bring judicial review proceedings on his own behalf.
However, on Wednesday, Deputy Judge David Elvin QC ruled that Mr Sanders had left it too late in launching proceedings seven months after the decision was made.
He refused to extend time beyond the usual strict three-month time limit for bringing judicial review proceedings.
The court was told that in July 2011, council officers granted permission for the former Focus DIY store at the Tavistock Retail Park, on the Plymouth Road industrial estate, to be split into two units.
However they failed to maintain the restrictions that were included in the initial 2007 permission for the building, limiting it to non-food retail use.
The council accepts that its fresh decision effectively paved the way for unrestricted retail use of the units.
But it says that if it revoked the planning permission it could face having to pay up to £500,000 in compensation to retail park owners Marchfield Properties.
In his legal argument, Mr Sanders claimed council officers acted unlawfully in granting permission, and misinterpreted the legal position, as they were wrongly under the impression that the restriction on food retail would remain in place.
He claimed that no reasonable decision-maker would have granted this permission.
However, Marchfield argued that it has incurred substantial costs in reliance on the planning permission and they would be prejudiced by the time it would take for a full hearing.
Marchfield's lawyers said that there were already other "impediments" in the way of the units being used by supermarkets including car parking which will require further planning permission.
A spokesman for West Devon Borough Council said: "We have not yet seen the full written judgement, and when we do, we will need time to consider our response before making any further statement."