Here is my example spreadsheet, hope that helps. So once again, in a nutshell if the day is selected as a non business day I need the contents of those cells to move back (left) to the last business day before the non business day...
IE... Saturday goes back to Friday, Sunday to Friday, Monday back to Friday, and if Friday was a non business day then it moves back to Thursday.
So Easter weekend for example in the UK would mean Good Friday, Sat, Sun and Easter Monday are non business ... so anything on these days would all be pushed back to the Thursday before Good Friday. I just cannot figure out how to do it.