The time of day will be returned as a number in the usual Inform time format: as hours times 60 plus minutes (on the 24-hour clock, so that the 'hour' part is between 0 and 23).

Constant TWELVE_HOURS = 720;
[ NumericTime hr mn word x;
  if (hr>=24) return -1;
  if (mn>=60) return -1;
  x=hr*60+mn; if (hr>=13) return x;
  x=x%TWELVE_HOURS; if (word=='pm') x=x+TWELVE_HOURS;
  if (word~='am' or 'pm' && hr==12) x=x+TWELVE_HOURS;
  return x;
];
[ MyTryNumber wordnum i j;
  i=wn; wn=wordnum; j=NextWordStopped(); wn=i;
  switch(j)
  {   'twenty-five': return 25;
      'thirty': return 30;
      default: return TryNumber(wordnum);
  }
];
[ TimeOfDay i j k flag loop ch hr mn;
  i=NextWord();
  switch(i)
  {  'midnight': parsed_number=0; return 1;
     'midday', 'noon': parsed_number=TWELVE_HOURS; return 1;
  }
  !   Next try the format 12:02
  j=WordAddress(wn-1); k=WordLength(wn-1);
  flag=0;
  for (loop=0:loop<k:loop++)
  {   ch=j->loop;
      if (ch==':' && flag==0 && loop~=0 && loop~=k-1) flag=1;
      else { if (ch<'0') flag=-1; if (ch>'9') flag=-1; }
  }
  if (k<3) flag=0; if (k>5) flag=0;
  if (flag==1)
  {   for (loop=0:j->loop~=':':loop++, hr=hr*10)
          hr=hr+j->loop-'0';
      hr=hr/10;
      for (loop++:loop<k:loop++, mn=mn*10)
          mn=mn+j->loop-'0';
      mn=mn/10;
      j=NextWordStopped();
      parsed_number=NumericTime(hr, mn, j);
      if (parsed_number<0) return -1;
      if (j~='pm' or 'am') wn--;
      return 1;
  }
  !   Next the format "half past 12"
  j=-1; if (i=='half') j=30; if (i=='quarter') j=15;
  if (j<0) j=MyTryNumber(wn-1); if (j<0) return -1;
  if (j>=60) return -1;
  k=NextWordStopped();
  if (k==-1)
  {   hr=j; if (hr>12) return -1; jump TimeFound; }
  if (k=='o^clock' or 'am' or 'pm')
  {   hr=j; if (hr>12) return -1; jump TimeFound; }
  if (k=='to' or 'past')
  {   mn=j; hr=MyTryNumber(wn);
      if (hr<=0)
      {   switch(NextWordStopped())
          {   'noon', 'midday': hr=12;
              'midnight': hr=0;
              default: return -1;
          }
      }
      if (hr>=13) return -1;
      if (k=='to') { mn=60-mn; hr=hr-1; if (hr==-1) hr=23; }
      wn++; k=NextWordStopped();
      jump TimeFound;
  }
  hr=j; mn=MyTryNumber(--wn);
  if (mn<0) return -1; if (mn>=60) return -1;
  wn++; k=NextWordStopped();
 .TimeFound;
  parsed_number = NumericTime(hr, mn, k);
  if (parsed_number<0) return -1;
  if (k~='pm' or 'am' or 'o^clock') wn--;
  return 1;
];