“The position here is very different. The tribunal is not being asked, as in Oxfam , to determine how much tax is due—that has already been agreed—but whether HMRC should be required to exercise their discretion not to collect the tax. That is not a tax dispute at all, but a matter governed by public or administrative law, and precisely the kind of issue which must be determined by judicial review. Nothing in the legislation could be construed as conferring any jurisdiction to determine such an issue on this tribunal, nor do I see any basis on which an argument of legitimate expectation that a statutory duty (as HMRC’s obligation to collect tax which is due is) will, or should, be waived could properly be regarded as the province of a tribunal whose task is to determine the amount of tax which is due: in that, there is a clear distinction to be drawn between this case and Oxfam . ”