A Which? Trusted Trader has to demonstrate to Which? they are competent, trustworthy have integrity and advertise and promote their business and services correctly. All qualifications, associated vocational training and certificates that are referred to on any advertising material, written correspondence, invoices or quotations are checked for confirmation. References are sought from 5 customers or clients, randomly selected from the past 12 months of trading then only after a further trading standard scrutiny is the business allowed to become a Which? Trusted Trader and advertise themselves as such and use the logo.