I am afraid that if you think that the financial crisis was purely caused by the US sub prime crisis then you are deluded. There has been a massive credit boom, which caused an asset price bubble. This had to be unwound, the US sub prime problem was the pin that pricked the bubble. This then caused a loss of confidence in the financial markets which are dependent upon confidence. Once confidence goes then the system goes as ably pointed out by Walter Bagehot in Lombard Street published in 1873. It is disingenuous to suggest that Brown's policies had nothing to do with this in the UK as he was more than happy for there to be consumption led growth leading to massive growth in credit. Further, he is responsible for continuing redefining the cycle for the purposes of the golden rule so he could continue to run deficit to pay for increased government spending when he should have had a surplus. Hence the parlous state of the UK's public finances today.
