Hi Erel, perhaps I did not explain it well enough...
The Betfair site loads a login page, which you log into.
Once a successful login is achieved, it redirects you to the main Betfair page, but there is encoded information (apparently) in the POST request that is sent to Betfair.
It is this request, from WebView to the server that we are expected to retrieve.
I only thought it might be Safari based as that's what the user agent says (and Mozilla, too!)