Well, that's a rather different situation.
The cause of the underlying collapse in the securitised mortgage market was borrowers being over-rated on credit worthiness and the securities derived from these mortgages then also subsequently being overrated. Market starts tightening, the underlying value of the overvalued securities starts becoming apparent and you've got a burst bubble and a general market liquidity problem, hence TARP and QE. All of which was sadly predictable - when the nominal lending institution is given a financial incentive to write loans without the balancing disincentive of default to ensure they only write repayable loans, or the equally strong financial incentive to overvalue their securities, why wouldn't they?
The US approach to this (all set up by Bush, lest we forget) is what's leading to this round of very reasonable lawsuits about financial fraud. The UK approach you've highlighted was rather different though. Northern Rock was completely sunk through illiquidity and is now wholly owned by the state. RBS was little better (thanks largely to a poor purchase of ABN AMRO) and is heavy majority state owned, Lloyds tried to buy the similarly sunken HBOS at a fire-sale price without doing proper due diligence, got into trouble and is now state owned to a lesser degree.
Let's not forget; the names are nothing more than proxies for their collective owners who reaped their profits. There is merit to sueing those who profited from the Fannie Mae / Freddie Mac debacle because the entities still meaningfully exist with continuity of ownership. This isn't true with any of the UK institutions; they made their poor decisions, their companies started foundering and to protect both depositors and the wider economy, the government stepped in, heavily diluted (wiped out with Northern Rock) the share capital of the owners who could no longer support the businesses and put new management in place. They aren't being sued in the way you propose because the responsible parties have already been penalised.