Running macro through button causing US date format - excel

Question

I have some code I run each morning that converts transactional data into a table then creates a Pivot Table based off of that data.
I have a button in a separate spreadsheet that I use to run these macros, but when I use the button the code formats the dates in US format not UK.
Sub TUFRFormat()
Application.DisplayAlerts = False
Columns("A:Y").Select
Selection.Columns.AutoFit 'Ensures data is displayed correctly
Columns("B:B").Select 'Rearanges columns to be presented correctly
Selection.Cut Destination:=Columns("Z:Z")
Columns("B:B").Select
Selection.Delete Shift:=xlToLeft
Range("F:F,G:G,H:H,I:I,J:J,U:U,V:V,W:W,X:X").Select
Selection.EntireColumn.Hidden = True 'Hides unrelevant columns
Range(Selection, Selection.End(xlToRight)).Select
Range(Selection, Selection.End(xlDown)).Select
ActiveSheet.ListObjects.Add(xlSrcRange, Range("$A$1:$Y$50000"), , xlYes).Name _
= "Table1"
Range("Table1[#All]").Select
ActiveSheet.ListObjects("Table1").TableStyle = "TableStyleLight9" 'Selects a table theme
Range("Table1[[#Headers],[Unit]]").Select
ChDir "P:\Desktop\Prior Day Journals\Tueday - Friday"
' Creates a pivot table based off of the sheet 'Data'
Sheets.Add After:=Sheets(Sheets.Count)
Sheets("Sheet1").Select
Sheets("Sheet1").Name = "Table" 'Adds new sheet and names it table
Sheets("Table").Select
Sheets("Table").Move Before:=Sheets(1) 'Moves to the first sheet in the document
ActiveWorkbook.PivotCaches.Create(SourceType:=xlDatabase, SourceData:= _
"Table1", Version:=xlPivotTableVersion14).CreatePivotTable TableDestination _
:="Table!R1C1", TableName:="PivotTable1", DefaultVersion:= _
xlPivotTableVersion14
Sheets("Table").Select
Cells(1, 1).Select
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Posted")
.Orientation = xlPageField
.Position = 1
End With
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Date")
.Orientation = xlPageField
.Position = 1
End With
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Year")
.Orientation = xlColumnField
.Position = 1
End With
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Period")
.Orientation = xlColumnField
.Position = 2
End With
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Unit")
.Orientation = xlRowField
.Position = 1
End With
ActiveSheet.PivotTables("PivotTable1").AddDataField ActiveSheet.PivotTables( _
"PivotTable1").PivotFields("Sum Amount3"), "Count of Sum Amount3", xlCount
ActiveSheet.PivotTables("PivotTable1").RowAxisLayout xlOutlineRow
ActiveSheet.PivotTables("PivotTable1").PivotFields("Posted").CurrentPage = _
"(All)"
With ActiveSheet.PivotTables("PivotTable1").PivotFields("Posted")
.PivotItems("(blank)").Visible = False
End With
ActiveSheet.PivotTables("PivotTable1").PivotFields("Posted"). _
EnableMultiplePageItems = True
I have tried looking for an obvious answer, but when I run the code directly rather than through the button it formats the dates as the UK format.
Any help would be appreciated