Both classes were still around in 1900, with most withdrawals taking plce from 1901 - 1904 for the C’s, and beginning in 1908 for the C1’s - many of which lasted until 1910/11 - the very last two being finally withdrawn in 1920 and 1924 respectively.
Summary of changes that occurred:
C no 77 - 96 until 1880: thence Nos 401 - 420.
Safety valves changed to Salter spring balance
Brakes added (as above)
Tender came in lowest-sided version with nos 84/5, sightly higher with all C’s, and highest with most C1’s
Various heights of steam dome were used on the tender over time - the tallest being earliest.
C1 nos 421 - 426 built 1882, nos 427 - 432 built 1884-7
The only visible changes that occurred were the reversing ever being fully exposed on the later batch, and the change of smokebox door with longer hinges for the later survivors.