You would be surprised at how many people walk to their bank with a cheque to pay for example their gas bill. They dont have a slip to go with it but they know they need to pay the cheque into such and such bank account.
When the gas co receive the money, all that shows on their bank statement is the sort code of where that money is paid in along with how much and the date.
The gas co, ask their bank to get a copy of the deposit slip that the teller created and the cheque.
Lo and behold the customer hasn't put the account number on the back of the cheque and let me guess, the payers name on the cheque is "Smith"
I wonder how many "Smiths" their are on the books of this gas company.
However, knowing the sort code where that person paid their money in and where the account is held, helps narrow down the search area. A Smith who lives in Leeds is less likey to pay in at a bank 100's of miles away.
The reason people ask for the address of sort code such and such is probably because they are trying to apply money to someones account.
So please, what ever the bill, put some reference on the back so they know who you are. Otherwise you'll just be contributing to some firms xmas party or shareholder payout.