help - how do you sign off a formal letter starting dear sir? faithfully or sincerely

[lilymum]

writing urgent letter that needs to go off tonight, and find the finer points of etiquette escape me. If starting dear sir, is it sincerely or faithfully?

faithfully

faithfully. Don't use two 's'es IYSWIM - i.e. Sir and Sincerely

HTH

faithfully

sincerely if you use the person's name.

Fully formall = faithfully

thank you very much to all the much better informed MNs than me for that!

if you know the surname it is sincerly

Does anyone know why?