Conditional drop down list

[elmuziko]

Afternoon all.

Struggling with a drop down query and seeking help.

So I have a new Active Directory User Account script built from an Excel file. One of the columns requests the office in which a new user will work in. This is an open cell as there are several hundred different possible locations.
Roughly 10 of these locations are major offices and what I'm trying to do is create a drop down list consisting of departments if any of these 10 locations are selected. If any of the 200+ are chosen then there is no list, or the list option is blank.

So for instance if my new user is in Head Office use list HeadOffice (which presents sub departments)
If the new user is in a porta-cabin don't offer a list or present a blank list.
If the office field is left blank or someone has button bashed the keyboard (jkh kl q3u l) don't offer a list or present a blank list.

If possible I'd like to do this without using a macro.

Thanks

[elmuziko]

Well I'm surprised this isn't something possible within Excel but on the off chance I've not done a very good job describing the problem I've attached a document which better goes through it.

In column E exists a drop down list detailing various office locations my new starters are in. Column F then has a dependable drop down list with departments.

What I want to do is take the drop down list out of column E, however if the user has typed London then column F displays the drop list for London. If they type Tokyo the drop down list for Tokyo presents itself. If they Type New York then no list presents itself.

Thanks