https://www.drinkaware.co.uk/check-the-facts/alcohol-and-the-law/drinking-alcohol-in-public-places In England and Wales it is legal to drink alcohol in public if you are over 18 years of age. However in certain public places (which have a particular order) if you are asked by the police to stop drinking, you have to stop drinking and give them the alcohol as well. So the characters could drink in public, yes. I'm not sure if the area by the London Eye is covered by this order or not though. In Scotland, it is a bit different. In Glasgow for example. drinking alcohol in public is banned. It was brought in to try and reduce alcohol-linked violence.