I wish to create a Data Validation Dependent Lists if a certain Value
appears in a Cell (say A1). I have looked at Contextures and it
explains it, but what if the value selected in my cell (A1) is =
London, then I want the user to type the appropriate values into the
'Data Validation cell' instead of from a dependent list selection. If
the value selected in A1 = Paris, then I wish the dependent list to
kick in.

The reason I ask is if London is selected, product codes (i.e. the
dependent lists) run to 100's, if Paris is selected I have only 4
product codes, so I would let the user enter for London but for Paris
they would select from only 4. Just makes things easier for me than
maintaining a dynamic list of 100's

Thanks