In order to open a bank account in London you need your ID, a cover letter by your employer and sometimes your passport (it depends on your nationality and the bank). I reasonably suppose that the same procedure works everywhere in the UK.
Anyway I was asked to help my Spanish friend to open her bank account (she strongly relied on my English ..oh my God). We chose the Lloid bank, where you can get a bank account free of charge. For the first time you get an appointment, generally within one week, you can go to the bank again to open your account definitely. After 3 days we went to the bank and finally we had a complete interview. Here an incredible thing happened to me.
The clerk was speaking in English to us, but she mostly talked to me because I was able to understand her and translate from a quick and "complex" English into a simple and slow English for my Spanish friend....a bit of gloat :)
I was a sort of electronic device which makes a good English broken :)
Anyway only after 20 minutes the clerk realized that I was speaking in English and not in Spanish and she said to me "But you're speaking in English!",
I replied: "Yes of course! I don't know Spanish, if you spoke slowly and easily my friend could understand you without my help" and the fretful clerk continued: "OK, I got it, we don't need you any more!!! " oh my God I hit the roof, the clerk made my blood boil !
I wanted to say: damn maroon you need more than 5 minutes to understand that I was speaking in English !!!! The interview lasted about 25 minutes, they are really thorough and I'd bet they collect enough info about you to have a complete profile of their client for legal and advertisement purposes.
In the end we went out and to celebrate the successful bank account opening.
Thanks, Zsofia for her corrections