New install, search not working

I'm sure this is a htaccess / rewrite issue. 

I have just installed litecart from scratch on a new instance of an ubuntu virtual server (16.04LTS), having installed Apache/Mysql/Php from packages. All seemed well, install page was all green, after setting write on some directories etc. 

Admin pages work great, look fine. Home store page looks ok, 3 test products added are showing ok. When I put anything into search, however, I get a 404. The url I go to on entering "red" and pressing search is /search?query=red

Installation definitely produced a root .htaccess (block comments removed) : it is below. Anyone have any suggestions for fixing it ? 

ErrorDocument 401 "Access Forbidden"
ErrorDocument 403 /error_document?code=403
ErrorDocument 404 /error_document?code=404
ErrorDocument 410 /error_document?code=410
ErrorDocument 500 "Internal Server Error"

# Deny showing indexes for directory content - Uncomment if supported by you web host
#Options -Indexes

# URL-rewriting
<IfModule mod_rewrite.c>
  RewriteEngine on

  # Tell PHP that the mod_rewrite module is enabled
  <IfModule mod_env.c>
    SetEnv HTTP_MOD_REWRITE On
  </IfModule>

  # Web path to catalog root
  RewriteBase /

  # No rewrite logic for physical files
  RewriteCond %{REQUEST_FILENAME} -d [OR]
  RewriteCond %{REQUEST_FILENAME} -f [OR]
  RewriteCond %{REQUEST_FILENAME} -l
  RewriteRule ^ - [L]

  RewriteRule ^.*$ index.php?%{QUERY_STRING} [L]
</IfModule>

# Deny access to content
<FilesMatch "\.(htaccess|htpasswd|inc\.php)$">
  <IfModule mod_authz_core.c>
    Require all denied
  </IfModule>
  <IfModule !mod_authz_core.c>
    Order Deny,Allow
    Deny from all
  </IfModule>
</FilesMatch>

# Cacheable external content
<IfModule mod_headers.c>
  <FilesMatch "\.(gif|ico|jpg|jpeg|js|pdf|png|svg|ttf)$">
    Header set Cache-Control "max-age=604800, public, must-revalidate"
  </FilesMatch>

  <FilesMatch "\.(css)$">
    Header set Cache-Control "max-age=86400, public, must-revalidate"
  </FilesMatch>
</IfModule>

# GZip compress external content
<IfModule mod_deflate.c>
  <FilesMatch "\.(css|js|svg)$">
    SetOutputFilter DEFLATE
  </FilesMatch>
</IfModule>```

Does this page work?
/index.php/search?query=red

If it does it could indicate that mod_rewrite is not working properly.