It is important to distinguish between an employee of a business and a consultant who provides services for the business.
Consultants are not afforded the full rights of an employee under employment law and are responsible for paying their own taxes. The relationship between a client and a consultant is simply contractual and subject to less statutory regulation than relationships under employment contracts. Employees are protected by a bundle of statutory employment rights and are paid through PAYE.
This agreement clearly indicates that this is a contract for services and that the consultant is an independent contractor.
For more information, read Consultants, workers and employees.