Wordpress + SSL + Varnish + Pound

Hello Im try install a SSL certificate with Pound and Varnish for a Wordpress site. The Proxy is an independent server, and has been running fine (few years) with varnish. I've used pound and this setup (90% the same) on many custom sites, so am sure the configuration there is correct and the SSL certificate is valid also.

Setup = http+https - Proxy (Varnish / Pound (Certificate)-Varnish) - Webserver

the https call works before I try and rename the site URL to https and have tried modifying the .htaccess file to force https but is creating a redirect loop and breaks. It also creates the same loop with just the site url set as https://

I've checked default.vcl and that is working fine and has no redirect conditions - was hoping the varnish redirect setup for a primary domain would allow me to ignore redirecting using varnish as the server has a number of domains running against it.

Where else can I look to check the redirect and ensure they are correct i.e. Must be http -> https -> http -> https.

Bit tricky to find the source of the redirect, any ideas?