The solution was to define a .htaccess file in the directory containing the editable content files that prevents browser cacheing. Obviously make sure this is only used locally during testing! This also requires the Apache module mod_headers - MAMP 1.9.4 (and probably other versions too) include this by default.
# when in local mode, never caches anything in this folder.
Header unset ETag
Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
Header set Pragma "no-cache"
Header set Expires "Wed, 11 Jan 1984 05:00:00 GMT"
Adapted from here: