Final update: by translating above findings into shortcode the site now works perfectly.
[count=’3′ more=’Load More’ photo_count=’100′] translated into shortcode:
\u0022count\u0022:\u00225\u0022,\u0022more\u0022:\u0022load_more\u0022,\u0022photo_count\u0022:\u0022100\u0022,
NB the ‘u022’ prefix is site specific.