We are departing from Heathrow airport at 1430 on a Thursday afternoon. Prior to that we will be in York. Is it crazy to think we can take a train from York that morning to make our connections and arrive before noon at Heathrow? We would love to make the most of our time in York, but don't want to be worried about the reliability of public transportation.
Carol, I would ask myself the following question: "What happens if I miss my connection?" While the European rail transportation system is generations better than what we have in the US, they do have maintenance, strikes and all manner of other things that could go wrong. I had the same situation of train from Edinburgh, catch a specific Eurostar to Paris same day. I have switched my plans to take out that unnecessary risk and will spend an extra day in London. Hope your trip is memorable. Bon voyage!
Let's work backwards from your 14.30 takeoff. You don't say whether it's a flight within Europe, or whether you are going back to the US. Assuming it's the latter, you need to be starting the check in and security process by 11.30. Trains from York arrive into Kings Cross. From there you can take a Piccadilly Line Underground train direct to Heathrow in just a shade under an hour. To be comfortable I'd want to be at Kings Cross by 10.00. You could get the Underground to Paddington station and then the Heathrow Express if you wanted to save a bit more time. Direct trains from York to London take just over 2 hours. The 08.01 departure from York arrives into Kings Cross at 10.03. If you wanted to add a little more time in case of delays, there are 4 earlier direct trains leaving York between 06.00 (arrives 08.13) and 07.35 (arrives 09.39). Amazingly, people do commute to London from as far away as York, but I've read reports which suggest that those early morning trains don't fill up until they get further south. So, it's achievable but not without risk. We have strikes, but they are very rare compared with places like Italy and France. Delays caused by overrunning weekend engineering works sometimes occur on a Monday, but won't be an issue for you. Trains do get delayed for other reasons like passengers falling ill, obstructions on the track and so on, but overall more than 90% of long distance trains arrive on time (which the regulations define as being within 10 minutes of the scheduled arrival time).
Thank you both so much for your replies. We've decided to reduce our stress by going ahead to London the afternoon before our flight.