That would be awesome. Take a peek at www.clickoak.co.uk - there were some other unsecure warnings (mostly due to the WC3 logo and autocomplete fields) but everything else seems to be sorted now ... just this one on selecting a shipping quote.

(Uh, you'll have to enter a valid UK postcode for the shipping address before it will fetch the shipping quotes - M187LL is the one I've been using for testing. Just because that's my home address.)

I did have a good long stare at the JS callbacks through Firefox and the Chrome JS console, but the only thing it's requesting when you pick a quote is https://www.clickoak.co.uk/?q=cart/checkout/line_items ... which is definitely returning correctly since that's the HTML for the price summary, which is displaying fine. And is also definitely secure.