Anyway, next time I will ask help from some agents :)

Actually, I have pretty big experience travelling through the border. So, I've got used to have as much evidence of my traveling as possible :)

Hm, probably you are right. I don't already remeber why exactly I decided to apply for this visa. But for what I see now, there are 2 concerns which would lead me to apply for the visa just in case: 1. There is sentence in the end when you get information about applying: You will not be able to transit without a visa if a Border Force officer decides you do not qualify under the immigration rules. You can apply for a transit visa before you travel if you’re unsure whether you qualify for transiting without a visa. 2. Second reason is from letter I received. I've updated my first post

I am from Belarus. Since some moment in the past it is already need transit visa for those who are traveling to the US through UK. As far as I know...

ok, thank you for the details. Actually, I need a transit visa. I naively believed that it would be enough to show my US visa and bank account with money...

yes, thanks. I have already read one of them. But it says reasons what officers want to see. It still not clear where I could fix that issue and they may approve. Or that there is no chances at all... I will have a look at another one you shared

But I have a text in my letter 'Your application is therefore refused under Paragraph V14 and V4.2 (a), (c) of Appendix V of the Immigration Rules.'

@NicolasFormichella Sorry, could you elaborate more?