And they would be, for when my Dad was living a street away he commuted from Bromley North and he told me that he regularly failed to get a seat. So, why don't they run 465s all the time?
The answer is, of course that the demand in the off-peak does not justify the use of the longer unit all day, indeed the off-peak could probably not fill a single carriage train.
There are a number of solutions that spring to mind-
1. Re-introduce the Bromley North- London direct service with a class 465, this would satisfy all overcrowding and would not be used in the off-peak.
2. Run the 465 on the shuttle in the peak and replace it with a 466 in the off peak. (seems rather obvious but I have a feeling it won't work, I'll look into it)
3. Run two 466s in a rapid service in the peak, ferrying passengers to Grove Park every 5 minutes or so as they come- they may have to wait at Grove Park but it would avoid overcrowding and the passengers would otherwise be waiting at Bromley North (or Sundridge Park) anyway (although Bromley North is much nicer to wait at in my opinion, Sundridge Park is even Nicer!) In the off peak one of the units would leave the branch and leave the other to continue the 3tph sequence. (alternitively the extra unit could wait in one of the two platforms at bromley north between the two peak times.