Thanks for your prompt responses and help.
I found another resource which gave me a clue on how to solve this.
I made a fresh installation, saved the two new configure files, then deleted the installation.
I copied the relevant parts of the new config files containing the correct paths to the old config files.
For reference here are the updated paths (maybe this will help solve this for someone else in the future);
define('HTTP_SERVER', 'http://www.shop.mydomain.com');
define('HTTPS_SERVER', 'https://www.shop.mydomain.com');
define('HTTP_CATALOG_SERVER', 'http://www.shop.mydomain.com');
define('HTTPS_CATALOG_SERVER', 'https://www.shop.mydomain.com');
define('DIR_WS_CATALOG', '//');
define('DIR_WS_HTTPS_CATALOG', '//');
define('DIR_FS_CATALOG', '/path1/path2/path3/shop/');
define('DIR_FS_SQL_CACHE', '/path1/path2/path3/shop/cache');
This now works :) except for one minor unknown issue...
I had a new admin theme set up but the admin section has somehow reverted back to the original zencart admin theme, even though all the files are the original ones in the new location.
Anyway, I'll figure it our or re-instal the admin theme.
Thanks again for your help.
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