Yes there is a register of licence holders , the local council/ licencing justices / police keep it.
If the person you are talking about has been convicted , you can report this to the police and or local licencing authority who will investigate.
The restaurant MUST have a premises licence which has to be on display where it can easily be seen. This premises licence has to show the name, address and contact details of the premises supervisor . Without this or if any details are incorrect the premises CAN NOT sell alcohol ! Serving alcohol without a licence is a serious offence , anyone including staff who serves alcohol in a premeses without a licence is liable to a £50 fine . This even applies to a temporary waiter/ waitress who just happens to take a bottle of wine / beer to a table. The premises owner is liable to a £50,000 fine AND 6 months in jail ! plus they will never get a licence again.
This is not bullsh!t, I actually know a man who owned a bar/restaurant who was convicted of criminal damage . He had to close down until his wife passed her personal licence holder course and was able to take over the running of the place.