As of my last knowledge update in January 2022, I don’t have specific information about Blake Lively’s Met Gala gown and Beyoncé’s regal looks being on display at Kensington Palace. The details you provided might refer to an event or exhibition that occurred after my last update.

To get the most accurate and up-to-date information about any exhibition featuring Blake Lively’s Met Gala gown and Beyoncé’s regal looks at Kensington Palace, I recommend checking recent news articles, official announcements from Kensington Palace, or the official social media accounts of Blake Lively and Beyoncé. Events and exhibitions involving prominent figures are often covered by the media, and official statements can provide details about the showcase.

If this is a recent development, news sources and official announcements will likely provide insights into the exhibition, including its purpose, duration, and the featured fashion pieces. Keep in mind that my information is based on knowledge available up to January 2022, and events or exhibitions may have taken place since then.