Do The EuroStarTrains Generally Run On Time?

The Eurostar is very punctual. I don't have any statistic on me, but it's a very safe bet the train will depart and arrive on time.

According to Eurostar, they are averaging over 90% on-time currently. It's been a couple of years since I took this route, but the train was on time both outbound from London and on the return from Paris. You must be heading to another European destination, because I believe the check-in time for long-haul back to the U.S. is more like 3 hours. Anyway, considering that the tube to Heathrow is about an hour on the Picadilly line, it looks like you could be okay with a 2 hour check-in as long as everything is like clockwork. For me, this would be cutting it too close...not much cushion should something go wrong. Have you considered returning to London the night before your flight, getting a good night's rest, and doing a little light sightseeing the next day before leisurely heading out to the airport?

I would count on the Eurostar being on time, if there are no more accidents in the tunnel. However, the Tube isn't always so reliable. In April the Piccadilly line was partially closed due to "engineering." I ended up arriving at Heathrow with only 1 3/4 hrs to spare after taking a detour around the Piccadilly line. It worked out ok and I still had plenty of time. I agree that arriving in London a day before departure would be a better guarantee that your timing will work out.

We took a cab from Heathrow to St. Pancras last June--it took about 80 minutes around noon on a MOnday.

A quicker route to HRow would be a cab to Paddington and the HRow Express.