9. Time shall be charged in units of 30 minutes or part thereof; and, except in relation to time under paragraph 10, 11 or 12 below–
(a)time shall apply from the end of the first hour at the place of execution until completion; or
(b)time shall apply after the messengers-at-arms has travelled a distance of 30 miles from his place of business until he returns to a distance of 30 miles from that place.