Tricky. The BOE wants them to raise more capital and yet the Government wants them to increase balance sheets via increasing lending to gov, business and consumer. The problem here is the capital issue and the BOE knows it.
The UK competes for capital, even over night excess reserves, with other countries, unless you impose capital controls, note.
If the BOE did more qe and widened the scope of qe this would help as the banks could be net sellers of high yield debt and even gilts so long as the qe program covered all the new issue government debt for the next year. Its possible but the Uk is increasingly in a squeeze here.
Watch the secondary market yield price for treasuries. If the boe comes under pressure on the overnight rate things would certainly get interesting.
Also note the cyprus issue which is burning on brightly.
http://blogs.marketwatch.com/thetell/2013/03/27/cyprus-faces-unprecedented-capital-controls-that-could-last-for-years/
Unsurprisingly Krugman comes out as an advocate of capital controls.. and states that the reason for the US housing bubble in 2007/8 was due to inflows of foreign capital. (I think he may have finally and completely lost the plot). Interesting why vast inflows of capital into the US system, according to Krug, would have lead to the US losing so much of her value in that decade or why so much investment and fund flow went to EM markets? Or why EM reserves mushroomed in the same period. No.. nothing to do with the US monetary policy. All to do with foreigners.
http://www.nytimes.com/2013/03/25/opinion/krugman-hot-money-blues.html?_r=0
As an aside, have you noticed a trend in the neo Keynesians. I have. They always and every where blame 'foreigners' for their mistakes which is why socialists lead you wars and free market capitalists towards peaceful commerce.
Great wrongs and minority oppressions can be done in the name of the greater good. Its always been thus. Hayek is a must read, on this and so many, issues.