A letter as an OISC Registered Immigration Firm, on our official letterhead explaining your right to work with appropriate references to the law and immigration rules. You can use the letter to prove your right to work in the UK. Not all employers will accept this letter. Therefore before booking service, please check with your employer that whether they will accept the letter from a UK Registered OISC Firm, regulated by OISC, UK Government.
https://www.gov.uk/government/organisations/office-of-the-immigration-services-commissioner/about
We can send letter to you and your employer (on your request) directly.