What to wear?

I'm going to a "Princess" party tonight (not a child's!) and have been asked to wear a long dress and tiara!!!! I have a sari from a long ago visit to India but I think the dress may win. I went to a wedding in it about 30 years ago and kept it for dressing up when I worked with children! If you keep a thing long enough......................! A 10 year old friend has lent me the gloves and the pound shop did well too!