is there away of searching through a string?

I have a long string about 130 characters as I have a LONG directory structure. but what I want to do is exact a small part of it.

eg. c:\1_london for may-06.xls
eg. c:\2_Kent for may-06.xls

I have two of the following files what I want to extract is just "London" and just " kent" now i thought of using left/Mid/Right but as you can see they are different lens.

Any help much appreciate