It is apparent looking at the numbering of pre-grouping locos that there was often no concept of numbering a class consecutively. Many railways had started off incrementing numbers as they built more early locos, but as these were progressively and randomly withdrawn, new locos were given numbers in the old series, commonly the lowest number available. After a few generations of this, the numbers would be a real scatter.
Also common was after 20 or 30 years, locos would be renumbered, sometimes by just putting an A suffix to the number, and a new one built would be given the number just vacated. Sometimes called the "Duplicate List". This could reach an extent that such a new loco, after its own 30 years, would be renumbered with an A suffix, and the previous A would still be around and have its suffix changed again to B. There were also renumberings within the sequence for no apparent reason. Large and small, new and old locos would have adjacent numbers.
I have seen described that it was an accounting feature, new locos charged to "revenue" would be given numbers within the existing sequence, while mechanically-identical new locos of a class charged to "capital" would be given numbers at the end. While the accountant is quite at liberty to do this charging, why it impacts on the actual running number affixed to the loco is not apparent. It is almost like there was a desperation not to "waste numbers".
The GWR seems to have been the first to make a break from this and ensure new locos were numbered in blocks, but others carried on as before.
Anyone know why it was done like that?
Also common was after 20 or 30 years, locos would be renumbered, sometimes by just putting an A suffix to the number, and a new one built would be given the number just vacated. Sometimes called the "Duplicate List". This could reach an extent that such a new loco, after its own 30 years, would be renumbered with an A suffix, and the previous A would still be around and have its suffix changed again to B. There were also renumberings within the sequence for no apparent reason. Large and small, new and old locos would have adjacent numbers.
I have seen described that it was an accounting feature, new locos charged to "revenue" would be given numbers within the existing sequence, while mechanically-identical new locos of a class charged to "capital" would be given numbers at the end. While the accountant is quite at liberty to do this charging, why it impacts on the actual running number affixed to the loco is not apparent. It is almost like there was a desperation not to "waste numbers".
The GWR seems to have been the first to make a break from this and ensure new locos were numbered in blocks, but others carried on as before.
Anyone know why it was done like that?