To be blunt, it's too long.
Para 1. Briefly introduce yourself, the applicant (include contact details for you both) and what your relationship is.
Para 2. A brief history of that relationship.
Para 3. Reason for visiting the UK at this time.
Para 4.Expansion or clarification of any points not fully covered on the application form.
Para 5. List of supporting documents submitted.
Para 6. Polite conclusion.