To quote Re: Is it possible to get the redirected URL?

LWP (or WWW::Mechanize) would let you load Page B and automatically follow the HTTP redirects, with the final URL being available to you in the uri method.

Doesn't that tell if you were redirected to the correct page?

You could also use WWW::Mechanize and set $mech->redirect_ok(0), thus not following the redirect and examining the returned header.