Done for 2.0.13:

File locking is now implemented for W32 (svn rev 4992).

The problem for me is that I'm using a Windows Roaming profile. That means I'm
using a COPY of my profile on 2 separate machines. Any changes on one machine
are not detected by the other. On logout, any changes are synched backl to the
Profile Server.
To get round this, I need to stop using the Windows Profile area to store keys.
I stumbled on this...
http://lists.gnupg.org/pipermail/gnupg-users/2008-April/033224.html
...and set my gpg.conf to the following...

There are two problems: The first is that GPA uses GnuPG-1, I need to check
this but it should not matter because the problem in T1008 is that the
gpgconf tool from GnuPG-2 is missing. There is no problem using both versions
of GnuPG at the same time.

Thanks for the info. This may be related to:
T1008
...where GnuPG2 doesn't get installed sometimes.

You are the first one to report this, despite that GnupG for Windows is 9 years
or so old. It is not only a problem with several PCs but if you run several
several GPG processes on one box. The file locking is simply missing.