We arrive at Heathrow at 10:45. We depart Heathrow at 4:35, could we possibly leave the airport and be able to see anything in London. Maybe even just visit a pub, or anything?

Just departed yesterday -- problem is that nothing is immediately around and Heathrow is a zoo. If you have to go through security,etc again, you should count on 2 hours because late afternoon is rush hour. If you are desparate to get away for 2 hours, assuming your luggage is checked through, you can take the Tube into London or you could check the connections and maybe take it out a couple stops (or take taxi) to Windsor, which is nearby & has a stop -- see the castle and have a drink and then reverse. It is about 15 minutes depending on traffic on the M4. Street by the Thames is scenic has plenty of pubs & restaurants. Not sure of the train connections though.

another thread had this under Heathrow & windsor:

Message: Windsor is a popular destination for Heathrow layovers. There is in fact a bus service for about 3.50gbp/person.

http://www.firstgroup.com/firstbeeli...r/windsor1.htm

A taxi costs about 20gbp each way.

I don't know how familiar you are with Heathrow. but while it's a zoo, it's also got a lot of shops and a few eating places airside,so a four hour layover may not be that boring. And changing terminals, if necessary, can take up quite a bit of time.
But if you want to be exposed to somewhere real-er than an airport, have an onward boarding pass and can get through immigration quickly there are three strategies:
- bus or cab to Windsor (the tube doesn't go there). 20 pouns or so by cab: see www.rbwm.gov.uk/around/bb_airoute-link.pdf for bus ttables
- get the Heathrow Express (not the tube) into London: 15 mins from T1/2/3: 20 from T4. And the most reliable train in Britain. Arrives at Paddington, which isn't too central, but if you just want to get out of the airport, download a local map from multimap.com and follow it to Hyde Park/Kensignton Gardens. You'll be able to have a walk, and just about make it to Holland Park and back again.
- tube to Osterley Park from LHR (also 15 mins): got to www.nationaltrust.org and follow links for Osterley Park, an ex-stately home.
Lastly, while we have a reputation for worshipping queues, if you mess this up, remember the mantra "sorry, my bus broke down on the M25", while elbowing your way to the front of the security queues coming back. I always find it works. But you need to be very assertive.

i think you have enough time to have lunch and maybe a quick look at shops IF your incoming flight is not delayed and you have checked baggage through, and you hold a boarding pass for your outgoing flight. I strongly suggest you take the Heathrow Express to paddington as suggested, and from there you could take the tube to Knightsbridge, where you could have lumch in either Harrods (food hall) or Harvey Nichols (sushi bar or fifth floor restaurant) and walk around for a little bit. or you could take the tube to oxford circus and do the same. just remember to arrive back at heathrow at least an hour before departure, it is a large airport and walking to the gate could take 15-20 minutes!

I think "can get through immigration quickly" is the operative question mark here. We arrived from USA on flight @9:30 am Sun May 18 -- took good hour to get through immigration/passport control. By the way, our impression was that that area had not been "freshened up" since our last time through 15 years ago. And then at least there were 2 or 3 people directing the queues. If you have British or EU passport, you have a better chance of getting though in a reasonable time.

By the way there are several "pubs" in Heathrow.

LOL, flanneruk

Quite frankly that is a tight schedule if you leave the airport and have hand baggage. The security at Heathrow is intense and you have to pass the gauntlet (British for lots of in- transit security checks) to each connection. Now, a much more fun option is to enjoy the dozens of fabulous DUTY FREE very high fashion boutiques in the airport while you wait!!!!Might cost you more than the whole trip, but sometimes better shopping than on the streets of wherever!!! And you might get some holiday and special occasion gift problems solved!!!Wind down, get a bite or slurp and take something to eat on board unless you like to gamble on airline food! POOOf! there goes 4 hours!! Bon Voyage!!!

We flew into and out of Heathrow twice, and while arriving was fairly quick [not from the EU], departing was incredibly time consuming. One time it took 'only' 45 min. to get through the screening. The first time we flew, it took us 2 hours to get boarding passes and get through screening. the line for screening went the entire length of the terminal [actually, two lines, one in each direction]. And, I heard people saying how they must go ahead, to catch a flight, and were told, "everyone is in the same boat".

My adivse is, it is not enough time, but Heathrow has a great selection of shops and several restaurants to pass the time in. Also, the duty free shopping there provided some good buys.

Thanks guys for the info. I think we'll just wait and see how long it takes and then see if we have enough time to do anything. I appreciate the advice.