A DEVELOPER would have to seek special leave from the Privy Council's Judicial Committee to argue whether a London silk would have to be admitted to the local Bar before he could appear before the Buildings Appeal Tribunal. The Court of Appeal, in refusing to grant leave to City West Investment Ltd to take its case to the Law Lords, accepted that the issue might be of great importance. But the court, comprising Mr Justice Litton, Mr Justice Bokhary and Mr Justice Mayo, was of the view that there was no action between the developer and the Bar Association that depended on the outcome. If the Privy Council considered it proper to entertain arguments on what ''acting as a barrister'' meant, it could always do so by granting special leave. The case began when City West wanted London Queen's Counsel Neville Thomas to appear before the Buildings Appeal Tribunal. It successfully obtained a declaration from Mr Justice Barnett that Mr Thomas was a ''paid advocate'' in the case, and that he could appear before the tribunal without seeking permission from the local Bar. The Bar Association, however, seeing that there might be a loophole in the law which would allow overseas lawyers free access to appear before the tribunal - took the case to the Court of Appeal and won. Despite the fact that the appeal before the tribunal had long been concluded, City West decided to seek leave to appeal to the Privy Council. City West's counsel told the Appeal Court that it would be in the interest of the developers for the ''ambiguity '' surrounding the law to be clarified, but Mr Justice Litton said any real issue between the parties had now been spent.