I've only just caught up with this thread and note with interest the very minor increase through St Albans City station. For those of you who are not aware the station is on a quite a bend, apparently due the St Albans city fathers building a new jail just where the MR wanted to run their line and shortly before they started building it.
In the end there was some degree of compromise and the MR was allowed to slice a corner off the jail grounds; this is very obvious in maps of the late 1800s, such as the one reproduced in the Middleton Press's "St Pancras to St Albans" book.
Be interesting to see if the slightly higher speeds rock the St Albans South box more than at present!