Investigatory Powers Bill

Could I press my noble friend a little more on Amendment 66? Of course I understand that there will be circumstances when written consent cannot be made, but there will be many other circumstances when it can be obtained. I note, for example, that it involves the consent of both parties. That suggests that it happens some time before the interception takes place. I should have thought it perfectly possible to have a proviso that the consent should in general be forthcoming and evidenced in writing, but that there should be a disapplication in urgent situations. In dealing with that matter, can my noble friend help me as to why we have subsection (2) as well as subsection (1) of Clause 42?