Are we eligible for a 2for1 by National Rail?

With those train tickets coming from and returning to Oxford, you should be entitled to take advantage of the 2-4-1 offers as many times as you want during the days in between ( and the travel days themselves).

My understanding of the “ nearest train station” requirement is that is is meant to deal with the problem of people buying cheap “dummy tickets” for the shortest possible train journey into a London station, in order to use the 2-4-1 offers that day. This was a trick promoted on TripAdvisor forums some time ago—I don’t know if it still is. But your travel into London is legitimate.

You will arrive at Paddington Station from Oxford. While this is not the “nearest” station to either Westminster Abbey or St. Paul’s, I would think they would quality. But if you are concerned, you might consider getting the paper 7-day Travelcard that will cover your travel in Zones 1 & 2 by tube and bus, and definitely can be used for the 2-4-1 offers. That is what we did in the past. But we kind of gave up the 2-4-1 thing in favor of advanced timed tickets for the things we really wanted to see. Then we didn’t have to wait in line. But maybe maybe that has changed and you can book a 2-4-1 in advance?

You are fortunate to be visiting in September. That is our favorite time for London, in part because of the month-long Thamesfest celebration of the River Thames, with cultural, artistic, educational, and historic-themed events on offer. You can see what is planned so far here:

https://thamesfestivaltrust.org/

We will be there ourselves in September for a few days.

@Lola A travelcard purchased from a National Railway Station will work for 2-4-1. A travelcard purchased from Transport for London will not.

@Lola thank you so much for your information.
Do I have to wait in line of those 3 attractions (Abbey, tower and St Paul) to get the 2For1 discount? If so ,that's not deserved the time. The London Pass may be a better choice?

@Carol can I get the 7-day London Zone1-2 travel card from the Oxford train station and use it for 2For1 offers?

Here is the information on using 2-4-1 vouchers for the Tower of London:

https://www.hrp.org.uk/tower-of-london/visit/tickets-and-prices/#gs.5sz52n

Scroll down, it is near the bottom. The offer can only be redeemed on-site on the day of your visit; it cannot be purchased in advance online.

You should check for yourself for St.Paul’s and Westminster Abbey. Things may have changed with covid, but when we visited these churches in 2015, 2016, 2018, and 2019, one could not get 2-4-1 tickets in advance; one had to show up and wait in line. After doing that once, we decided it was so much easier to book our discounted Senior tickets in advance, rather than use the 2-4-1 vouchers which require waiting in line and then paying full price ( not the discounted Senior rate) for one ticket to get the other ticket for free.

If you have rail tickets that go into the slot at a ticket barrier to open the gate, DO NOT put them in the slot as you will not see them again as these are your proof that you arrived by train. Instead, by the ticket barrier, you will see staff. Tell the staff that you need to retain the used ticket as proof of arrival in London by train. (The 2 for 1 attractions might ask to see proof of travel by train). You can then get the 2 for 1 deals during your week in London.

PS> If you have a print at home train ticket - you scan this at the ticket barrier and it is yours to keep.

Two points
There are 2 routes from Oxford to London, Paddington and Marylebone
The cheapest tickets are called Advance Single where you have to travel on the booked train. They start from £5.40
Suggest you consult www.seat61.com for information on rail travel in UK
The credit card size tickets are being replaced by paper tickets with QR codes which you scan so gets rid of the risk of tickets being swallowing by the barrier slot

Paper 7-day Travelcards are no longer sold by National Rail stations in London since June, only the Oyster variety which is no good for the offer.

However, if you have the tickets for Oxford->London Terminals (*) and the return journey, together they would be valid for such locations that you list.

As already mentioned make sure you don't put the outward portion of paper tickets into the barriers as they won't usually be returned. For convenience you may prefer to buy online so you can retain copies of the e-tickets either as pdfs or within a mobile wallet.

(*) Depending on the ticket you buy it will be to London Terminals or Paddington/Marylebone if specific to the operator. This does not matter.

@Lola thank you so much for your input again.
I followed your instruction about these 3 attraction with 2For1. Only St Paul can get an advance ticket. Westminster Abbey and tower of London need to wait in line to get the offer. I may have to consider a timed ticket to the tower of London. However, I heard Westminster Abbey's line moves quick without reservation. What's your experience with the Abbey line up? I am going to there around 1pm and join their 2pm guided tour if possible.

Thank you for all for all the tips. Very helpful!

@Carol now

I read some other post of yours that without a reserved ticket to Westminster abbey, you still get in there 5 mins including line up for the admission?