Reliability of UK trains... should I build a buffer?

You don't need to be there 75 minutes in advance. The deadline is 30 minutes (and even that is already ridiculous). So that 75 minutes already contains a buffer.

And Eurostar will put you on the next available train if you miss your connection due to a delay on an UK domestic train.

The 11.56 looks doable, unless you are a slow walker, but has no wriggle room.

I'd go for one of the earlier ones, but I don't like rushing.

Assuming you've already bought the eurostar ticket you might want to think about a CIV fare into London: Man in Seat 61

If you arrive 30 minutes before departure, you will definitely miss your train. The gate closes 30 minutes before departure. You still have to go through security and French immigration (Schengen) before boarding the train. And that's before getting to the gate.

They will not definitely put you on the next train. We're talking about a Sunday in June. It may be sold out. Sunday is a very busy travel day on the trains.

You also have to keep an eye on maintenance schedule to see if there are cancelations and or last minute problems.

When I got up that morning, I'd see if there are any problems on the line. Then, Id probably get the 11:28 at the lastest. Worst case scenario you have lunch at St. Pancras

This type of question always elicits the same response in me: what is the advantage of cutting it close? Why not have your leisurely morning in London instead of Oxford? Why would you not just take the earliest reasonable option, and spend any unnecessary time just shopping or getting a coffee in London? IOW, we as responders know the consequences of getting there late, but we don't know your consequences of leaving early.

Listen to FrankII, not WengenK on this question.

I would probably take the 10:56 or 11:16 so I would have time for lunch at St Pancras before getting in line for checkin, emigration, immigration, and security.

Thank you all for the advice, it’s very helpful.

darrenblois, the main reason we would prefer a later train is that my family are generally not morning people… and this is part of a two week trip so I’m looking for opportunities to let them sleep later. Additionally we only have one night in Oxford versus five in London (earlier in the trip), so sleeping in and getting breakfast in Oxford is more appealing than spending time in London.

I'm a bit wary of cutting things really fine on a Sunday morning rail journey from two unpredictable factors:

• Overrunning engineering work. There is nothing really major planned for that weekend but more minor overnight work can overrun into the morning disrupting or stopping service.
• Sunday is not part of the normal working week for certain GWR staff contracts. If there aren't enough volunteering to work then some services won't run.

I would get the earliest train from your list or even an earlier one than that and have a nice lunch in London. Sunday is the worst day for trains and I really wouldn’t want to risk missing the Eurostar. It depends how risk averse you are though!

You must get to St Pancras by the time recommended on your ticket….75 minutes pre departure…. as you have to go through Border/passport control to go from the UK to any other country, in your case to France.
They will not “put you on the next train” if you are rushing in at the last minute and miss the train you booked.
You would have to prove that the train you were on to get to St Pancras was delayed.
You’ve got lots to choose from to get there in plenty of time, so you really have no need to cut it fine.
It’s summer and very busy and trains are reserving early, so you might have to wait quite a few hours to get the next service to Paris….as in hours, or even days.
It’s summer…get up early in the sunshine…get to London early and have a nice meal or coffee while you wait.

Note: if you get the CIV ticket mentioned in the Seat 61 link they should put you on the next available train (which might not be the next train) if you miss the eurostar because the connection is delayed. But that is only if you miss the connection due to delays not other reasons.

The CIV ticket is priced differently so do the maths before you make a decision.

I'm going to pile on and strongly urge you to take an earlier train. There is simply too many things that could go wrong and result in missing the Eurostar. Especially on a summer Sunday. Which is worse- getting up in the morning or missing the train to Paris?

The advantage of the CIV ticket is that it may be cheaper during the morning peak, but normal tickets now also offer you a protected connection, as Eurostar is now part of the AJC.

Regarding being there on time: If Eurostar really wants to be "as annoying as flying, but slower" then they will lose me permanently as a customer. From Oxford I would be compelled to just fly out of Heathrow.

Regarding the 30 minute cutoff: The gate actually closes 15 minutes before departure. If you are late because of a delayed incoming train they will not strictly enforce that 30 minutes. (Just like airlines don't do this either).

Wengen K is NOT correct in saying that normal tickets offer you protection. That only happens if you buy a CIV ticket from Oxford to London International, and only then if you have allowed a 75 minute connection at St Pancras, so a 90 minute connection between arrival at Paddington and schedule departure from St Pancras.
Aiming to arrive 30 minutes before departure is madness.
Yes you may possibly get through security, and UK exit and French entry checks in that time, but they will categorically not hold the train for you.
Do anything else and you are buying a new Eurostar ticket.
I would take the 1056 or at a pinch the 1128.

Regarding the 30 minute cutoff: The gate actually closes 15 minutes before departure.

The 15 minute gate closure is for business class passengers. 30 minutes for standard class.

I have taken Eurostar numerous times and have seen the gate cutoff restrictions taken seriously. While I'm not someone who gets to the airport three hours before a flight, I do stick to a 90 minute arrival prior to Eurostar. I've seen line backups and serious delays going through French Immigration.

But you do as you wish. You can believe about a ten of us who all agree or one who doesn't.

Build a buffer. Things happen. An accident on the tracks, an electrical failure, you name it, it can cause an unexpected disruption. Time gives you an opportunity to go to plan B.

I think you'll be ok with the 11.28am train, but I certainly wouldn't leave any later than that and would consider leaving earlier if you were comfortable. Sometimes the queues for the Eurostar can be very long- but they do separate them by train time, so you're only queuing with other people on the same train as you. I try to arrive about the recommended time- sometimes even a bit earlier. With extra time you can stop at M&S (or wherever you want- there are lots of options at St Pancras)- to get snacks for the train. Once you get through the gate you have security and then two separate passport queues. On the other side there are seats and a few places to get food/drinks- so even if you are extra early going in you can just hang around there. Sometimes all the seats are taken but once the next train departs they free up.

Thanks all. I will probably end up taking the 10:56 train.

The CIV option seems like a good one. Unfortunately it does not seem to be available for puchase online, only a paper ticket. The Seat61 site mentions trainsplit.com is the only online retailer. But on trainsplit the search results for Oxford to LNE (London International for Eurostar) say 'paper ticket only'.

The results say paper ticket only- but that does not mean you can't buy it online.

Merely that you will be e-mailed a collection code to collect the tickets from a ticket machine at Oxford (or any other station in the country that you are passing prior to Oxford). Collection can be at any time after purchase. As opposed to having an electronic ticket.

I couldn't find them on the Scotrail, LNER, Avanti, Northern or Great Western websites last night (yes I have spent a lot of time on this query). I know the station code is not always LNE but still couldn't trace them. Which is odd as they can be purchased on demand in person from Northern Rail Ticket Vending Machines.

You could also buy from a ticket clerk at Oxford (or any other) station

"Wengen K is NOT correct in saying that normal tickets offer you protection"

Actually I think I am correct. Eurostar joined the AJC agreement a few months ago, and so now your connection is always protected, provided you planned enough buffer. They even mention that on their own website.

https://www.eurostar.com/uk-en/travel-info/connecting-train#Missed-Connection

If I were in the OPs position I would take the 11:56. That gives you 98 minutes. Enough buffer.

You should understand that the 75 minutes Eurostar advises is so that you have a buffer. There is no need in my opinion to add even more buffer.

Even if you hang your hat on the AJC the 1156 is still too tight. Trains from Oxford arrive at Paddington, Eurostar leaves from St Pancras.
That is a 15 to 20 minute transfer normally.

At 20 minutes that gives 3 minutes leeway.

But the official MCT between any two London terminals is 40 minutes. It used to be 60 minutes.

That is the yardstick of measurement for AJC or CIV 40 minutes + 75 minutes.

The 1128 is the last service to meet those minima.

From the Eurostar website Wengen linked to:

If you miss your Eurostar train:

Chat to a staff member who works for the UK train operator you’re travelling with. Confirm that your train has been delayed or cancelled. At London St Pancras International, our team will get you on the next available Eurostar train for free.

Please keep in mind that the next available train may be a service later that day. Staff will always offer the best possible option, but on very busy days, you might have to be booked on a train on a subsequent day.

Read the last paragraph carefully. On a Sunday afternoon in June, I doubt the Eurostar trains will be empty. Are you willing to spend an extra night in London if necessary?

I travel a great deal and I'm pretty good at timing things. But when it comes to train connections, I add a little extra time just in case. I've been through too many "just in cases." (Like one train being canceled two minutes before departure.)