If you are one of the many Brits just a little annoyed today this is probably the petition you'll want to sign. Reminder that you do need to be a British citizen with a valid UK address and that you need to enter a genuine email address, since it's used to confirm your signature.
Really hoping that Boris sees sense on this one, given that he's throwing away any vestiges of legitimate government if it goes ahead. Also posted at https://ffutures.dreamwidth.org/2173588.html, where there are comments. Please comment here or there using OpenID.