Originally Posted by stut
LCY is fairly easy - just get the shuttle bus to Liverpool St, and you can get a (slower than King's Cross, but not bad) train from there.
I imagine it is frequently faster to take the Tube from Liverpool Street to King's Cross than to take the slow line up from LST. When I come with a lot of baggage, however, I prefer to just take it from Liverpool Street.
Also, the shuttle bus from LCY to Liverpool Street costs
£6!
I wouldn't bother with the Heathrow Express. It is a waste of money if you are going to have to transfer via tube afterwards.