they cannot check but they can/will surely ask for updated bank statement i.e. POF. It usually comes with Medical Request and PCC etc. I don't it would be matter as long as u have the sufficient amount of POF any any bank or by other means.
I beg to differ your view. They can check anytime as per the powers assign to them by applicant. Practice may differ from theory. But will only confirm the accuracy of statement submitted to CHC and nothing else. Bank will never let them know what is the status of funds on the date of inquiry.
asyousuf