here's the BOE analysis that's already been put up earlier:

http://www.bankofengland.co.uk/publications/Documents/quarterlybulletin/2014/qb14q3digitalcurrenciesbitcoin1.pdf

the only reason i repeat it here is b/c of the last footnote in the Annex of Technical issues where the author mentions the Nash Equilibrium for mining.  he must have picked that up from me in this thread as i was the first to identify that concept afaik. 

he, and the BOE, are here.