If I'm sending a letter to London, then on the return address, should I put United States on it?

Question

If I'm sending a letter to London, then on the return address, should I put United States on it?

Answer 1

It isn't a requirement to put a return address on the envelope.  However, if the recipient doesn't accept the letter, it will not be returned to you.  

Answer 2

yes,a proper letter has the senders full address and country

Answer 3

Yeah will save a lot of hassle if the letter goes on the missing list, write your full address and country that way if they cant deliver it will get back to you