so theoretically if tfw wished in the future any these specs could relatively simply be improved?
Not quite, the only spec that could easily be tweaked are the top speeds as it would seem to just be a software limiter that does this.
Power, tractive effort & acceleration are all limited by the kit onboard, the 755s and 756s already operate at the apparent limit when powered from OLE. The 231s are limited by the output of the engines but it would seem that if fitted with 25kV equipment should also be able to match the peak acceleration & T.E. of their sisters
And from what I understand over at Anglia, the performance of these units, even for the 231s on diesel, is going to be mind blowing compared to what they're replacing.
There's really no point in tweaking their top speeds unless TfW change the routes they're allocated to. 75mph is the maximum speed on the Valley lines, and even that's only for a relatively short distance. Most of the time the 756s will be at 60 or less - and given the short distances between stations there seems little reason to improve that (the acceleration of these units should provide better journey times by themselves).
The maximum speed for the 231 routes is 95 if they're allowed to run at HST speeds - otherwise 90. Again, the improved acceleration over the units they're replacing should provide a decent upgrade without needing any changes to top speed.
Thanks; good to know that the suituation should improve in future.
Indeed it should. There are another 3 drivers finishing off their training this very week, and experience with dealing with the stock itself is growing every day.
The numbers of loco trained crew at both Crewe and Cardiff depots is due to be effectively doubled through next year to account for the Swansea - Manchester services so that should have a positive impact on the reliability of the Holyheads when there's a larger pool of both crew and stock available for both routes.