Converting String Dates From UK To US Format

I have hit an issue when tranfering a string date from VBA to excel, excel thinks the string is US format and swaps around the days and months even though the system and excel are setup for UK date format:

Simple example of the problem:

Sub test()
Dim testy As String
testy = Now
'testy will equal 04/10/2007 17:20
Range("A1").Value = testy
'A1 will equal 10/04/2007 17:20
End Sub

Now I know in this example that if I used DateValue(testy) it would work, but our situation is a bit more complex as we are running this is a loop testy is not always a date.