That's an absurdly slow roll-out. Something is clearly going badly wrong if it's that slow.
They don't have enough staff, it's a long training course for drivers and pretty tight cost control. It was never going to be quick. The glimmer of hope is that the expansion onto several other routes probably means that most other depots will be doing 701 training and getting enough of a link trained for one diagram is usually the slower part.
Clearly. I’ve never seen a rollout at such a consistently slow pace.
And to clarify, the webpage makes it out as if all months only have 1 new diagram (rather than some 2 as mentioned in the post you’re replying to), looking at the train number column..!
This is why I stress it’s almost impossible that they’ll be able to cover for all the 455s by the end of 2025 if this rate continues. They’d have to really ramp it up after June to even get remotely close.
Each row is one new diagram, the Entry Into Service months are the same for some rows. Some of the rows would need to switch over together to keep the diagrams balanced, taking February 2025 from what's currently in the Network Rail schedule data:
Train #7
Y18436 5H05 0619 STRAWBERRY HILL C.S.D. - KINGSTON 0629
Y18095 2H05 0640 KINGSTON - SHEPPERTON 0705
Y18665 2H14 0711 SHEPPERTON - LONDON WATERLOO 0807
Y18671 2H13 0812 LONDON WATERLOO - SHEPPERTON 0905
Y18643 2H22 0911 SHEPPERTON - LONDON WATERLOO 1004
Y18670 2H21 1012 LONDON WATERLOO - SHEPPERTON 1105
Y18647 2H30 1111 SHEPPERTON - LONDON WATERLOO 1204
Y18706 2H29 1212 LONDON WATERLOO - SHEPPERTON 1307
Y18633 2H38 1312 SHEPPERTON - LONDON WATERLOO 1404
Y18698 2H37 1412 LONDON WATERLOO - SHEPPERTON 1505
Y18833 2H46 1511 SHEPPERTON - LONDON WATERLOO 1604
Y18705 2H45 1612 LONDON WATERLOO - SHEPPERTON 1705
Y18652 2H54 1711 SHEPPERTON - LONDON WATERLOO 1804
Y18655 2H53 1812 LONDON WATERLOO - SHEPPERTON 1905
Y18697 2H62 1911 SHEPPERTON - LONDON WATERLOO 2004
Y18669 2H61 2012 LONDON WATERLOO - SHEPPERTON 2106
Y18649 2H70 2111 SHEPPERTON - LONDON WATERLOO 2204
Y18654 2H69 2212 LONDON WATERLOO - SHEPPERTON 2305
Y21184 2H78 2311 SHEPPERTON - LONDON WATERLOO 0004
C03925 5Y42 0026 LONDON WATERLOO - CLAPHAM YARD SIDINGS 0055
Train #8
Y17834 5H87 0545 CLAPHAM YARD SIDINGS - LONDON WATERLOO 0600
Y20698 2H87 0615 LONDON WATERLOO - SHEPPERTON 0716
Y18626 2H94 0730 SHEPPERTON - LONDON WATERLOO 0833
Y21737 2R15 0845 LONDON WATERLOO - LONDON WATERLOO 1009
Y20916 5Y86 1022 LONDON WATERLOO - WIMBLEDON PARK DEPOT SDGS 1109
+
Y15976 5V49 1633 WIMBLEDON PARK DEPOT SDGS - LONDON WATERLOO 1649
Y20825 2V49 1707 LONDON WATERLOO - LONDON WATERLOO 1832
Y20711 2H97 1843 LONDON WATERLOO - SHEPPERTON 1929
Y18657 2H64 1936 SHEPPERTON - LONDON WATERLOO 2034
Y18716 2H63 2042 LONDON WATERLOO - SHEPPERTON 2135
Y18694 2H72 2141 SHEPPERTON - LONDON WATERLOO 2234
Y18632 2H71 2242 LONDON WATERLOO - SHEPPERTON 2336
Y18819 5H80 2341 SHEPPERTON - STRAWBERRY HILL C.S.D. 0002
The above might be inaccurate as the schedules could be altered before they switch over, some will require alteration where they don't currently balance.
With 5 units introduced in first five months, 10 in next ~6 months there is a small rate increase. While there are 82 class 455s, roughly need 30-35 10-car class 701s in service to displace those depending on other fleet changes. The next 10 gets a third of the way there, it's likely a further rate increase in the second half of next year and any remaining gap might be coverable by other stock/formation reductions while a few more diagrams await going over to 701s.