Thank you Richard, again, for your speedy response.

I'll try to further clarify the process in response to the points and questions you've raised

In response to your Questions:
1. Actually, to err on the side of caution, I will revert back to my original idea of having the rows LOCKED (based on the 4 hour criteria) and then copied to the Master Log workbook - because if there is a break in the link to the Master (IT moving/renaming folders ) then there is a possibility of loosing data etc. It also allows the Dispatch to review events of his shift.
2. I understand that the Code for the Master Log workbook will need to be contained in the Daily Log workbook. The developer tab will not be visible and the level of knowledge of excel is very basic and have no idea, so I don't believe a password to get into the VBA is necessary.
3. The idea of copying the data into a separate workbook is because the file will get very large and previous experience has shown that Excel is likely at some point to corrupt the workbook once it gets past the 5-6MB size. Excel handles the file well under the 6MB. Another consideration is also, the larger the file, the likelihood that the file will start to lag in performance (become less responsive).

Further clarification:
1. The Daily Log is pretty much continuously open, and it is the Dispatcher who enters the time based on when a call comes through, this is not VBA generated.
2. The Dispatcher completes the details of the call as information comes in and saves the open file, which remains open.
3. The Dispatchers have strict instructions to not sort the file, which they have followed. (Password protection to prevent sorting, would that effect/conflict with the VBA code?)
4. The structure of the sheet is that the new entry is added to the next line of empty row, working down the sheet. So it would need to lock and copy the data starting from row 2 and down to the period that meets the '4 hours' cut off.
** Just as an aside in case it has any bearing on the proposed process - there are sheet has multiple excel functions and formulas (VLookups, etc - non VBA), calculations of time
differences from time of call, to dispatch, to on site and leaving site.

I would be able to work out how to transfer the data, but the coding to setup the scheduling of the 4 hour criteria based on the Time (24hr clock) in column 'K' of the preceding row, I have not a clue how to code that.

So in summary, we are not deleting the contents of the Daily Log file, but just locking the rows and copying it to a separate Master Log workbook (password protected)

Is the information a little more clearer than my first attempt? I hope so

Thank you again for your time
Cheers,
ShyButterfly