First for the new Third Class

This from Rover...

Charging a first class fare for standing or squatting in the vestibule?

Every penny counts!

UPDATE: This from Chionanthus Virginicus...

Presumably where it is necessary to use an external door of a First Class vestibule when joining/alighting at stations with short platforms, a punishable offence has been committed?

Better extend the dwell times then!!

UPDATE: This from Strawbrick...

The no standing in a 1st vestibule with a 2nd Class ticket rule has been in force for at least 57 years. I was 10 years old when I was so told by a Ticket Inspector (sic) when he found me standing in the Corridor (sic again). 

Happily my Mother was able to show him both our first class tickets.

Also, I think you will get short shrift on a flight if you went and stood in Upper/Business/Executive/Club/etc... class with an Economy Ticket ...

I also think something similar applies aboard ships.

The problem is that passengers get upset when they see empty 1st Class seats when Standard Class is full and standing and the train crew do not see fit to exercise the option to declassify the 1st sections. 

They do not do this for a number of reasons:

1. The possibility that passengers may ask for refunds of upgrades; and 
2. That 1st Class passengers might complain vociferously
3. Or more likely, that Control haven't autho!

And yes, I do travel 1st Class because... (err... so do many Eye readers! Ed) And yes, I do ask guards why they have not declassified. 

The answers include "I didn't know I could", I have been told not to" and (best of all) "I would have done, but i could not get through the train to check because it was too full"(!).

One final point, when I started commuting on 310's the 50% uplift in fare was matched by a 50% uplift in space (no knocking of knees) and much more comfortable seats. 

The uplift is still 50% (and some off-peak savings are not available) whilst the extra space has typically shrunk to something like 20% and on the Southern Trains to CLJ the seats appear to be exactly the same.

But of course I take your point on the unnecessary aggression in the notice.
There is no automatic "fine" as the notice would imply, as you have the option of moving or staying but paying for an upgrade.