Planning permission issued in error by Wirral Metropolitan Borough Council six years ago has been quashed by the High Court.
Mr Justice Kerr said exceptional circumstances meant a challenge could be brought long after the normal time limit for judicial review.
The case of Thornton Hall Hotel Ltd, R (On the Application Of) v Wirral Metropolitan Borough Council  EWHC 560 (Admin) was brought by the Thornton Hall Hotel against Wirral, with its business rival Thornton Holdings as an interested party.
Thornton Hall Hotel, and Thornton Holdings’ nearby Thornton Manor, are competitors for hosting weddings and functions.
In December 2011, Wirral granted unconditional planning permission for three marquees in the grounds of Thornton Manor, without any time limit.
Wirral and Thornton Hall Hotel argued that this was an error that should be rectified as the council’s planning committee had intended permission should depend on several conditions, one of which was that it would lapse in December 2016.
However, the document formally granting the permission erroneously omitted all the conditions.
The marquees therefore remained in place after December 2016 with bookings continuing to be taken.
The judge said: “I am satisfied that the decision notice did not faithfully reproduce the decision made by the planning committee and that the cause of the error is likely to have been, at least, human failing.”
He said he would allow the case out of time as Thornton Manor “bears considerable responsibility for the lateness of the claim because it knew of the error and chose to remain silent about it”, adding “In my judgment, the court should now exercise its power to rectify the error by quashing the permission.”
This was because “the planning permission that was issued is not as it should be” because they are in Green Belt and were intended to be permitted only because hiring fees would pay for restoration of the adjacent gardens.
The judge added: “The interested party ran its commercial operation at Thornton Manor from 22 December 2011 knowing that the presence of the marquees after 19 December 2016 would be, at the very least, a matter of possible controversy and possible legal challenge.
“It was not, in my judgment, realistic to rely on expiry of the three month limitation period without also bringing the issue into the open, which the interested party decided not to do.”
He said: “Given the failure of the interested party to draw the LPA's attention to the apparent error, it is unattractive then to assert that the claimant and the LPA bear responsibility for the delay in the matter coming to light”, and he rejected the argument that Thornton Manor had marquee bookings to honour until 2020 since it enjoyed planning permission for this only by “keeping silent about the obvious error that had been made”.