From Cambridge train to King's Cross St. Pancras Underground Station, Tube to Paddington (H&C Line)-Underground, then walk to London Paddington Station. 1 h 5 min £23. From Cambridge train to Liverpool Street Station then line 205 bus to Paddington Rail Station. 2 h 2 min £24. From Cambridge drive to London Paddington Station. 1 h 12 min £11.