Guidelines for restaurants, pubs, bars state
"The opening up of the economy following the COVID-19 outbreak is being supported by NHS Test and Trace. You should assist this service by keeping a temporary record of your customers and visitors for 21 days, in a way that is manageable for your business, and assist NHS Test and Trace with requests for that data if needed. This could help contain clusters or outbreaks."
Then go's on to say ....
"Many businesses that take bookings already have systems for recording their customers and visitors – including restaurants, hotels, and hair salons. If you do not already do this, you should do so to help fight the virus. We will work with industry and relevant bodies to design this system in line with data protection legislation, and set out details shortly."
They also have to ensure that in door gatherings are limited to 2 households in support bubbles.
The same applies to outdoors but they can also include group of at most 6 people from any number of households. A gathering of more than 30 is illegal and if found then action can be taken.
It may not be law but if they look not to be playing ball and not limiting numbers or managing people waiting to get in or wanting to leave. Which it also say's they need to do the LA can will soon sort them out. As Local outbreaks are all down to them to manage and they have to carry the can.