Why have you listed "government stakes in RBS and Lloyds" on the liabilities side? These are assets - they may prove over time to be poor investments, but they are not debts in the sense you imply. The comparison to Carillion fails because nation states are not commercial ventures. To understand this you need to consider who that national debt is actually owed *to*.
Think that one through and you will be on the path to enlightenment...
PDR