transit visa?

[pbgirl 1]

I saw postings for this elsewhere, but I really need to make sure and clarify the answers.

My husband is flying in on British Airways, stopping through London for the connection.

I understand that you don't need a direct transit visa if you have a valid US visa. Is the K3 considered a valid US visa even though it hasn't been stamped and thjis is his first time entering the US? What I mean is, I thought the "visa" itself was not givein to you until the POE. What the Embassy gives you is actually the paperwork for the immigration officer to admit or deny you at POE. I know I am getting into semantices here but this is important since he is traveling so soon.

According to the British Airways website:

Important Note: Direct Airside Transit visas are required by nationals of the following countries, even if not entering the UK or changing airports during transit: Afghanistan, Albania, Algeria, Angola, Bangladesh, Belarus, Burundi, Cameroon, China (PR), Colombia, Congo (Dem Rep), Congo (Rep), Côte d'Ivoire, Ecuador, Eritrea, Ethiopia, Gambia, Ghana, Guinea, Guinea-Bissau, India, Iran, Iraq, Kenya, Lebanon, Liberia, Macedonia, Moldova, Mongolia, Myanmar, Nepal, Nigeria, Pakistan, Palestinian Territories, Rwanda, Senegal, Serbia & Montenegro (including documents issued by the United Nations Mission in Kosovo), Sierra Leone, Somalia, Sri Lanka, Sudan, Tanzania, Turkey, Turkish Republic of Northern Cyprus, Uganda, Vietnam and Zimbabwe.

Isnt my husband still technically a national of India?

Do we have to get a transit visa for him? Please help!

[pbgirl 1]

OK, also found this online at the uk visa website:

A valid US immigrant visa packet (form 155A/155B) is a 'valid visa' for DATV exemption.

Is this what the sealed brown envelope is?