There appears to be a little confusion over what HMRC’s guidance on Bitcoin means.
The most obvious thing to notice that it is a VAT Brief. So it is primarily aimed at stating what HMRC’s practice is for interpreting UK and EU VAT provisions in relation to Bitcoin.
One of the purposes of such guidance is so that taxpayers can show reasonable care by taking into account HMRC’s view. I don’t think you can reasonably read any policy decision by the UK government into the statement. It is just HMRC explaining its view of existing law.
But HMRC does go to the effort to lay out briefly the tax treatment, stating that normal principles apply. So it seems the natural conclusion that Bitcoin mining would be treated as a trade if it fulfils the badges of trade. Any significant profits created in the UK through mining would almost certainly meet that criteria. Other increases in value achieved through Bitcoin are subject to normal rules. So businesses using Bitcoins as currency could find out HMRC’s view through the Business Income Manual, such as here.
Obviously, as with their statement on VAT, HMRC are trying to explain how the current rules apply to Bitcoin. They are not making any statement of policy on behalf of the UK Government.
Indeed, the Chancellor is going to deliver the Budget very shortly, so I would expect any policy decisions regarding Bitcoin to be included there.