Bankers had very little to do with bringing the UK economy to its knees. This was all driven from the US decision, under bill Clinton, to get more people taking out mortgages, critically that they couldn't afford, and the somewhat interesting rules in the US about what happens in foreclosure.
In order to encourage the mortgages, someone had to back them. This was the US government in the form of Freddie Mac and fannie mae. The US government encouraged that these mortgages be securitised, because without this, they couldn't go on buying votes, and then the Bankers got involved.
Essentially, the US government was allowing millions who couldn't afford it to get into massive debt. Similar things followed in the UK as lending rules were softened, led by the direction of, yes you guessed it, the government, and thus a generation living eternally on the never never was created, but this wasn't just in one country. It spread globally.
Then the unthinkable happened and there was a recession in the US. People lost jobs and couldn't afford their too expensive mortgages. So they dumped them, and funnily enough, did it East to west in the US. This brought the two government agencies to their knees and the securitised products were now known to be toxic, driving their value down. These products were interlinked into all parts of the financial system and the result is what we saw.
The fault of whom? Well the Bankers are the easy target. The reality is the politicians and the public taking advantage of what the politicians offered. And in the UK during this period it was the labour party. Blair, brown and balls.
So no, the Bankers aren't the prime reason. Politicians buying votes are. But don't let a good fact get in the way of a Russell Brand-esque story....
And the economy growth? The majority of that was coming from government spending (I believe it was around 2/3rds), so you have to ask how it was maintainable?