Where, however, as here, the basic background is one of volunteer service, the call-out is on a basis that there may be exemption on compassionate grounds, the recalled reservist is given repeated opportunities to voice any concerns, as a former serviceman he is familiar or at any rate required to be familiar with the Queen's Regulations and as a recalled serviceman he has, as is conceded, access to those Regulations and to the Leaflet, we do not think that it makes sense to say that the appellant has manifested his belief until he has informed his service of it, and has done so in a formal way. ... In effect, a volunteer cannot say that his conscience or religion has been interfered with by the state until he has made it clear in some appropriate and suitably formal way that he is no longer a volunteer.