As far as space in 1st is concerned, I can only report what I saw on that particular train at one point in the journey. For the rest of the time I was jammed in a seat with a large suitcase between my knees and the seat in front (the train's suitcase rack was of course full)
As far as the Train Managers are concerned, my question was whether they (or anyone in the chain of command) had authority to improve the crowded conditions. From some of the answers above, it seems that they had, but they chose not to.
It is also worth mentioning that this train had collected a lot of holidaymakers on its journey through Cornwall and west Devon. At Newton Abbot there were many more, because it is the link to the line down to Torquay and Paignton. Holidaymakers all have luggage, which adds to the congestion. This was a long, long journey of many hours that overran by a further 30 uncomfortable minutes. If GWR want to encourage holidays by train they will have to do much, much better. I heard no mention of Delay Repay, yet this was a case where large numbers of people should be claiming.