As of that time, I don't have specific information on the number of active serial killers in the UK. Additionally, tracking the exact number of active serial killers can be challenging, as their activities are often clandestine, and law enforcement agencies usually keep such information confidential to protect ongoing investigations.
It's important to note that serial killers are extremely rare, and their presence in any country, including the UK, is a matter of concern for law enforcement and public safety. If you have concerns or suspicions about criminal activities, it's crucial to report them to the appropriate authorities immediately.