National Railway Trains in London

You don't use the National Rail in London. You use the tube.

2-4-1 Travelcards Step by Step Instructions

Read carefully and make sure you buy from the right station.

Yes, you're a tad confused, "in" London you will be generally using the tube, buses and DLR not National Rail trains. The paper travelcard 2 for 1 offers for those modes of travel works because of a loophole, IF the travelcard is bought at a National Rail station (they promote the offers).

OH MY GOSH---I think I FINALLY have it figured out!!!!!!! I had read the Trip Advisor site, the National Rail site, many posts several times. It just never registered that, after buying the paper ticket at the proper rail station, you then use the tube or bus or whatever to get to the attraction to use the 24l offer. DUH!! I reread it after the replies above and the lightbulb went off. So then I had to figure if it is wort it financially to go to the bother--and it was. For others who follow and read this it works out like this: paper travel card is 24 pounds per day for 2 people, admission for 2 seniors to Westminster Abbey is 32.20 pounds, and for Winston Churchill War Room and Museum 15.20 pounds for a total of 64.40 pounds---should be doable on Saturday. Using Oyster PAYG (not including the 5 lb purchase because you get it back) the daily cap is 6.60 so for 2 people is 13.20 lb plus admission for 2 for both those places is 64.40 lb equals 77.60 lb. A no brained---77.60 - 56.20 equals 21.40 lb savings. It would be even more savings if we did a third 241 attraction that day as you can do as many as you like, but I want to be realistic for a July Saturday and fit in doing something else free. Did I finally get it right? And thank you for your help--what a process this has been.

Why did my reply print in big blue words? I am not shouting.

You can re-edit and preview before you post to ensure it looks OK

Also the lbs - either use £ (it's on your computer somewhere) or GBP

On a US Windows keyboard try

Shift and AltGR and 4
or
Shift and Ctrl and Alt and 3

On a Mac
Option key and 3

https://en.wikipedia.org/wiki/Pound_sign

On a US Windows keyboard try
Shift and AltGR and 4
or
Shift and Ctrl and Alt and 3

Alas, those methods may work on a UK keyboard, but not on a US one (we don't even have AltGR on US keyboards).

Instead, press and hold Alt, then press 156 on your number keypad (the ones to the right of the letter keys, not the numbers on top of the letter keys). Let go of the Alt key, and voila!

Or, just cut and paste the £ symbol. Or, say GBP (every currency has an official 3 letter abbreviation; for US dollars, it's USD).

In the US, we know what you mean by "lbs," but this is not used in the UK to mean currency (I don't even know if it's used to indicate weights).

lb. is a pound weight
£ is a pound money
So something may be priced as "£2.50 / lb", except it won't, because prices in shops in the UK must be shown primarily in Kg, so it will be "£5.50 / Kg".
US and UK keyboards are different, they are also different in every country in Europe. If you haven't got the correct symbol, or the symbol is ambiguous, just use the standard 3-letter abbreviation, as used by banks, airlines etc. This is usually the official 2-letter abbreviation for the country plus initial letter of the currency:
GBP EUR (an exception to the rule) CHF DKK PLZ USD CAD AUD etc.

Thanks for the notice of using GDP--honestly had not noticed that as most places have the correct symbol. I was trying to save space using lb instead of pound all of the time so nice to know the correct use. And I will preview and edit so it doesn't turn blue this time. Thanks again. Well, darn, I touch the gray box for Preview and there is no preview and edit so now what do I do? Hope this doesn't turn blue as well.

The typeface issue was due to the line of dashes typed at the bottom, which I have now deleted. Various symbols are recognized as part of web design code. Sometimes you have to play around with editing your post to find the troublesome character.