Vista - Query Active Dir group where name contains *

I am trying to find the members of an Active Dir group in code, but
unfortunately the name of the group contains "*". I have no problem
returning members of any other groups we have.

I have tried:

searcher.Filter = "(CN=*Chester Ground Floor)"
searcher.Filter = "(CN=\x2AChester Ground Floor)"
searcher.Filter = "(CN=\2AChester Ground Floor)"
searcher.Filter = "(CN~=Chester Ground Floor)"

The first option times out because it finds ALL groups.
Second returns null
Third says "invalid escape sequence" and won't compile
Last one returns null

I know the group name is correct because I can return it in a list of all my
groups.
I have also tried fully qualifying the filter (OU=) etc.

Any advice gratefully received.

Dave.