Unlike PR firms, legal firms in the UK are bound by anti money laundering Know your Client Regulations. It requires customer due diligence including identifying their customers and checking who they say they are, and requires enhanced due diligence when you enter into a relationship with politically exposed persons including taking measures to establish where the person's wealth and the funds involved in the business relationship come from.  https://www.gov.uk/guidance/money-laundering-regulations-your-responsibilities