I was initially interested when I first saw this last year, but it turns out to be complete FUD. See http://www.revk.uk/2013/12/paraniod-ravings.html for the take on the original disclosures from the MD of one of the UK's most technical ISPs (and believe me, he's no fan of BT's).
In a nutshell, some ISPs will effectively hijack publicly routable ranges for internal use if they know that there's no way those addresses will ever be used for real public services. In this case, a UK ISP is re-using the US DoD's 30.0.0.0/8 network. Anecdotally I've heard the inverse is also true (US ISPs use UK MoD ranges).
See also http://www.ispreview.co.uk/index.php/2013/12/confusion-alleg...
In a nutshell, some ISPs will effectively hijack publicly routable ranges for internal use if they know that there's no way those addresses will ever be used for real public services. In this case, a UK ISP is re-using the US DoD's 30.0.0.0/8 network. Anecdotally I've heard the inverse is also true (US ISPs use UK MoD ranges).