Originally Posted by
alanR
1) is terrible as it means you have to get on a Tube in Central London at a time when 3 million people are trying to get home and like 3) it also means you are trying to get on a train with some of those 3 million people
Which leaves 2), the best of a bad bunch as it leaves someone else to do the driving & you don't have to haul luggage up & down stairs and along platforms. Have you considered NOT going to Cambridge on that day or having an early dinner and getting something later when the chaos dies down?
Do you mean 2 (HEX), or do you mean 3 (National Express)? "Leaving someone else to do the driving" and "no hauling luggage along platforms" would suggest that you actually meant 3.
1 and 2 look about the same to me, with 1 (Piccadilly Line) probably meaning less hassle because one start one's journey on a relatively empty train at LHR, and it would be direct to Kings Cross. Of course the Tube would fill up as it gets into Central London, and, as you say, the train to Cambridge would be pretty packed as it's a commuter route at commuting time.