By Yours sincerely, Word order

If you know the name of the person you are addressing - e.g. if you started the letter Dear Mr... then you should end the letter Yours sincerely,... If you do not know the letter of the person you are addressing - e.g. if you started the letter Dear Sir or Madam or To Whom It May Concern, you...

In British English that is incorrect. If you know the name use Yours sincerely; if you do not know the name use Yours faithfully. We have covered the Yours sincerely/Sincerely yours topic before and came to the conclusion that the first is British English word order and the second is American...