Did you just ignore the previous post on this? I agree 2-3K is not a lot of money to me either, however it would be unusual for me to pay it in in cash. Likewise it could be a lot of money for someone else who is usually overdrawn and again unusual to be paying that kind of money in. Or it could be totally normal that you regularly make cash payments into the bank account.
The banks are obliged by law, around the world this is not just the UK, to file suspicious activity reports, so if you do this regularly then there is nothing suspicious about it. If you do it as a one off and act like a normal reasonable human being and tell them briefly what the reason is; i.e. sold a car, a customer paid in cash blah blah. Then again no issue. But if you get all uppity about it, they won't have to tell you (by law) but chances are that a SAR gets filed for you.
https://en.wikipedia.org/wiki/Suspicious_activity_report
Yes it has an American bias but it is a world wide system...
But hey ho, naturally you know better and just get all uppity about it and tell the banks and police and everyone else to mind their own business. I could recommend a bank in Luxembourg and Liechtenstein that may be able to help you unless you want to keep it under your mattress.
As you were