Thanks Mick.

I currently have a copy of the ParseData code under Private Sub Worksheet_Activate() with a check so it will only run if there is no data in the sheet.
What I need now is a manual update option.
I did think about adding a dialog at the start of the Worksheet_Activate() to ask if an update is required and then remove the data exists check but I do not know how to do this.

I managed to get a dialog box designed with text and two option buttons but how to get this to display and then receive the information on which button is pressed is beyond me. I was thinking that one button would return true and the other false.