I can recommend the following program as being a great help in searching parish records for those ancestors who aren't where you hoped they would be!

It essentially consists of a database of about 15,000 parishes, with their ordnance survey grid references.  The basic program runs under dos.  You give it the name of the parish you are interested in, and specify a distance around that parish.  The result is a listing of other parishes within the specified distance of the original parish.  Then 'all' you have to do is to check those out
Another version runs under MS Access.  This gives the distance and direction of each listed parish from the original parish.

The programs can be downloaded (they're freeware) (about 2.5 Mb when unzipped) from
http://web.onetel.net.uk/~gdlawson/parfind.htm
They have been compiled by Gerry Lawson with the help of the SussexFamily History Group.

There is also a program available from a different author, Robert Slade, but using probably the same database, which has the additional feature of accepting parish names in soundex code.  Its result format gives the OS reference of each parish as well as the distance from the original parish.

It may be downloaded (freeware) (about 1Mb unzipped) from
http://www.robslade.demon.co.uk/index.htm