If one has the time, it can be worthwhile experimenting with train reservation costs by breaking a journey into different sections.
An example would be Exeter to Bristol, then Bristol to London - as opposed to Exeter to London. Once purchased, the journey times are the same; the total cost can often be cheaper.
An example would be Exeter to Bristol, then Bristol to London - as opposed to Exeter to London. Once purchased, the journey times are the same; the total cost can often be cheaper.