A closer reading reveals that 11 billion (I assume that's thousand million) pounds was the projected cost at the time for completion of the system. "Only" 2.7 billion, or 4.3 billion USD, has been spent, although I don't know if there are contract terminations of serious size to be paid.

Still, it's an epic failure, said to be the greatest single one in government IT contracting.

(E.g. I'll bet the FAA's eternal quest to upgrade from their 1940's (sic) technique and '60s or so architecture has cost more over time, but not any single failed effort.)