BudgieBoy

You probably could find as many people who want it the other way.

You could take two routes.

1) In existing workbooks - To change all 'currency' formatted cells in one
go. Go to Format>Styles>Currency>Modify... change it to Currency and ok out
of dialogs. This will reset the 'currency style for this workbook and all
cells formatted as 'currency' will be changed immediately and future button
presses will format this way for this book

2) Re-purpose your currency button by inserting the below code in
personal.xls

Sub NewCurrencyFormat()
Selection.NumberFormat = "£#,##0.00;-£#,##0.00"
End Sub

and then right click on any toolbar, select 'customize'.  With the dialog
showing, right-click on the currency button and select 'assign macro...' and
select this code.  This will re-purpose the button for all future
applications of 'currency'

You could also have a button which sets the currency for existing sheets (as
1)