I am currently sat in the rear carriage of a Marylebone bound Chiltern Railways service.
The train has one carriage less than usual. That fact is noted on the Chiltern Railways website, which is usually kept well updated.
The only trouble is, there have been people standing since I got on. At present there are eleven people standing in this back carriage. It will be much busier up front.
Every one of those people will have stood for more than 20 minutes on a peak time arrival into London.