The Planning Inspectorate ruled in favour of the appeal submitted by arcade owners Holland Park Investments Ltd (HPI), who had refused to accept Kensington and Chelsea Council's decision to continue restricting trading there to Fridays and Saturdays.
The appeal followed a highly vocal campaign by the Portobello Antique Dealers' Association (PADA), the Save Portobello Facebook campaign and others against HPI's plans.
The campaigners fear that antiques dealers, who spend much of the week sourcing goods around the country for sale in the arcade on Saturdays, would be squeezed out in favour of other traders who would be prepared to open all week if permission for seven-day trading was given.
They still fear that dealers may be forced to choose between opening for seven days or quitting their leases, going against the traditional spirit of Portobello and creating a precedent that would spread to the rest of the area.
However, the planning inspector believes their fears are unfounded: "It is by no means inevitable that removal of the condition [restricting trading from the basement to Fridays and Saturdays] would automatically lead to the cessation of the antiques trade," paragraph 26 of his report argued. It added: "In this eventuality it is said that the antiques area would 'disintegrate' but the overall scale, diversity and reputation of Portobello Road makes this seem unlikely."
Regardless of the risk, stated the inspector, existing permissions did not restrict the use of the basement or ground floors to antiques-related business anyway.
The inspector did restrict loading and unloading times in the interests of people living nearby, and banned deliveries from Vernon Yard, saying they should take place only from Portobello Road itself.
PADA chairman Costas Kleanthous, who played an active role in the appeal process, was grateful to the inspector for giving opponents of the idea "every opportunity" to put their case, but said the decision effectively gave developers "carte blanche" to do what they wanted.
"We're examining our options based on this decision, and we don't see this as the end," he told ATG.
"The inspector was fair and even-handed, but his decision to award partial costs against the council raises the question as to whether the council's handling of the case was robust enough to protect local interests and amenities."
His statement referred to a separate judgment by the inspector, in which he awarded HPI 30% of their costs to be paid by the local authority.
The inspector ruled that the council had acted unreasonably in refusing the original application, because they had not provided sufficient evidence to show the alleged damage they said the changes would cause and which contributed to their grounds for refusal of the plans.