Formal salutation in letters.

[Fraser McLean]

I have to write a letter to a Duke. I know to address him as 'Your Grace', but how do I end ther letter before my signature where 'your sincerely', or 'yours faithfully' would normally be located?
Thanks.

[Anglika]

You start with "Dear Duke of xxxxx" and you end with Yours sincerely.

See here : UK Parliament - How do you address a Lord?