Will a 24" suitcase fit in the overhead on the Eurostar from London to Paris? I'd like to be able to keep my luggage with me.
Thanks.

I think it will fit in the overhead, but I am sure someone else on this board has actually tried it. When we took the Eurostar we put our larger luggage in the luggage area in the car we were sitting in. It appeared to me that each car has a place for passenger luggage. Our "carry on" when overhead. I don't recall seeing anything larger then a duffle on the overhead racks.

I think the issue is really how "thick" your 24 inch is. Those upper racks aren't very high, but are plenty deep otherwise. I have seen some smaller bags not fit because they were to thick.
On most trains there are also some big spaces between the seats that go back to back. That is a good bet if it won't fit overhead.
I'd suggest you get onboard as soon as possible. I've seen some Eurostar trains that looked more like luggage cars than passenger cars! Are all those people moving permanently or what?

We were just on the Eurostar from London to Paris about two weeks ago. We put our 21" rollaboards in the passenger luggage section and our smaller bags in the overhead. The train cars are not that big so even though we were almost at the other end of the car we could see the luggage racks. Also, keep in mind there are no stops until you get to Paris, so I really think the concern of someone taking your luggage is minimal (if that is what your concern is).

People were getting up before the train stopped to retrieve their luggage, so you could do that as well. Or try to get a seat closest to the luggage area. They are just open racks in the car.

Your 24's are probably pretty heavy so count on putting them at the end of the car. It will be totally safe. But there will be a LOT of luggage there and many other bags may end up on top of yours.