Also, with my experience of government, your letters never reached anyone with any understanding let alone authority within each organisation. I can assure you that there are smart people in government who know about Bitcoin and have been looking into it as I have met and discussed it with them. But these people are probably above the pay grade of the £20k pa staff handling these requests. And their job is basically to make all these Freedom of Information requests go away so they stop bothering everybody else, as quickly and efficiently as possible.
Another thing to bare in mind, is that at BIS (and I suspect other government agencies and departments too) there is a focus to destroy all information not immediately useful. This way they can truthfully answer "we don't collect this information", which is a lot cheaper than actually fetching, reviewing and releasing it.