When they banned alcohol in economy, I took a small bottle of wine on board from the business lounge. When I was served with my dry on board sandwich, I put the wine on my tray table. The steward said I was not allowed to bring my own wine on board. I replied it was not my own wine it and was supplied by KLM. He went to ask the Cabin Manager and she said no it was not allowed. You could hear the groans when others were asking for beer etc.