"We appreciate that every effort has been made to try and reduce errors in making the correct calculation at the time of the sentence, but experience has shown that there are greater practical difficulties in eliminating errors than seems to have been appreciated when the legislation was enacted and brought into force. It may seem straightforward to ascertain the number of days, but experience shows that it is frequently not so. Defendants often offend more than once and may be on remand in relation to one set of proceedings but not another. Others, like Johnson in this case, move in and out of remand. In the case of yet more, the position is confused by absconding and its consequences. The addition of a curfew calculation will plainly add to the danger of administrative uncertainty as to how many days are to be counted. As these cases show, any error may often not be picked up until well after the elapse of even the 56 days now allowed under section 155 of the Powers of Criminal Courts (Sentencing) Act. As we have endeavoured to set out, needless expenditure is incurred for no apparent gain."