What is the difference between Business Fully Flexible and Leisure Select Fully Flexible? There's a minimal price difference between the two, but there's a big difference in price between the Fully Flexible and Semi-Flexible. Why such a high premium on flexibility? Thank you.

You commit to a date then it's cheaper in advance. If you can't commit (fully flexible) then you're charged more for the privilege of changing your date if you wish.

Prices go up the closer it gets to your travel dates and when the cheaper priced seats have all been sold

The Eurostar runs just like airlines in terms of capacity control.

The least popular times cost less than the most popular.

Buying in advance gets better fares than waiting until the last minute.

And once you're ticketed changing from one time to another can cost a fortune.

this is one reason senior (60+) and passholder fares (need a pass valid in UK, France or Belgium) are such good deals for one-way travel - they are about the cheapest often and can be changed without penalty up to the time of the train

that said if no seats remain in your fare category changing may be impossible.

In the US i always advise calling BETS 800-441-2387 with such questions - it doesn't matter if you are buying on eurostar.com in pounds or euros they'll still expertly answer your questions like these; they also book them and i say always get a quote from both sides - at times $ prices can be lower than often are not - there seems to be little correspondance to the two pricing systems so check both. I know of no other source where you can ask such questions like the difference between fares by phone - perhaps in UK numbers.

Thank you for the information!

the key is really to book early

especially as certain periods - like school vacations in both UK and Europe can really book things up

or this fall for three weeks around the Rugby Cup in Paris

or a big soccer match, etc. You never know

weeks around Easter, etc.

but be sure of date as cheaper tickets not refundable or changeable, except senior, youth and passholder fares in theory but still need to have seats remaining in those categories to change.

The London-Brussels route seems much more available than London-Paris where that route has captured some 70% or so of all London-Paris travel i read.