Fares are normally sky high on Eurostar on Sundays - but there is a day return of about $90 that is sold in very limited numbers - reseerve far in advance to get that one. www.eurostar.co.uk or www.sncf-voyages.com

Yeah you can return to London the night before. But accommodations in London are more expensive than in Paris, from what I've found.

So you may want to calculate the difference in ticket prices for a flight on the morning of from CDG to LHR versus a Eurostar ticket and then also account for the difference staying an extra night in Paris vs. London.

The other thing I noticed was that Eurostar tickets booked at the SNCF site are a bit cheaper than the one booked at the Eurostar.com site, which is denominated in pounds IIRC.

"The other thing I noticed was that Eurostar tickets booked at the SNCF site are a bit cheaper than the one booked at the Eurostar.com site, which is denominated in pounds IIRC."

If you delete your cookies you can go to the Eurostar site & try entering it as a different nationality & find out the fare for your trip. I've found recently that pretending to be American worked out to be several quid cheaper & being French even lower BUT it was harder to book a trip FROM the UK.

Note however you can't guarantee that a given nationality will always give the best prices on Eurostar

Here's an update.

My traveling partner and I didn't want the stress of figuring out whether we could make it back to the airport in time... it just wasn't worth it for us.

We decided to go back to London the day before, and since I was able to find the Eurostar Two for One deal, this turned out to be a great bargain. I was able to redeem a free night at the Sheraton Belgravia for the last night that we are in London before heading off for LHR in the mid-morning our last day.

Huzzah! :))

You might wish to post where and how you found the Eurostar twofer. It might well be the last word in the "fly or train" debate.

Sure...

Eurostar is offering a promotion through the Telegraph newspaper for people to book two for one tickets to Paris and other locations. It came out to 58 GBP for two people, round trip! Fantastic bargain.

http://eurostar.com/UK/uk/leisure/la..._promotion.jsp

You have to get the passwords for the promotion though, which are available here:
http://www.buyonegetone.co.uk/exclus...-telegraph_134

Make sure you follow the instructions carefully. The rates are only available on certain times and days, so if you're flexible this could save you a good chunk of change!