Wrong declarer, dummy and defenders
At a recent club evening North reached 6 Diamonds doubled in a contested auction. North then proceeded to lead, East put her cards down as dummy and all played to the trick before someone said this is all wrong. Yes really! Well it was very hot and late in the evening. AS it was a friendly session and we were short of time, I asked them all to take an average minus and get on with the next board. By chance the contract if correctly played would probably have been a middle. If it were a serious session what should have happened please, just in case it does occur again?