As a matter of fact the train journey time to Stratford averages out at 46 minutes and that to Liverpool Street at 56 minutes. I don't quite understand you saying that "... you won't do it in 45 minutes." Many times you'll do it in that or less. I'm travelling by train to SEN this morning and returning tomorrow afternoon so I'll make a note of the actual times taken and report back.
Let's hope you weren't on this morning's 10:55 departure from the airport which got to Stratford in 51 minutes and just got into Liverpool Street in 60 minutes.
No more train stories from me - the mods have shown their dislike of trains on here previously.