Originally Posted by
iapetus
It is admittedly worth considering.
So, how would this actually work? UA
#923 is scheduled to land at 12:20pm. I am assuming that my bag will be checked through. How soon can I reasonably expect to arrive at Paddington Station? And at what time would I have to board the Heathrow Express to make a flight that departs at 5:15pm? It could be a lot of stress and money for not much time in London. On the other hand, if a decent pub can be quickly found and a good football game can be caught (I think I saw that Everton is playing that afternoon), not that I'm a Premier League fan, the adventure might be worth the effort.
Heathrow Express runs pretty frequently. Should get to Paddington by 1:30 (1:15 if everything clicks). It ain't cheap. 25 pounds each way. TFL is 10 plus change and is only 8 minutes slower w/ 4 stops, but probably 1/2 the frequencies. You'd want to be on a Express no later than 3:30p for a 5:15 departure w/ no luggage. That realistically leaves only 2 hours out and about from Paddington. Probably not worth it.
There's a pub I've eyed out on Bath Road bordering airport (Three Magpies) on the occasions I've spent the night out there prior to a flight, but have never visited. There's a free bus that might get you there.
5 hours is just a bit under for the trouble of to/from central London, but (in my opinion) more than I want to spend in an airport lounge.