Great Northern operates a train from London to Cambridge hourly. Tickets cost $24 - $35 and the journey takes 47 min. Greater Anglia also services this route hourly. Alternatively, National Express operates a bus from London to Cambridge every 4 hours. Tickets cost $9 - $13 and the journey takes 1 h 51 min.
From London Kings Cross train to Cambridge. 47 min £22. From Aldgate, Mansell Street bus to Cambridge, Parkside (Parker's Piece). 1 h 51 min £9. From London drive to Cambridge. 1 h 12 min £11. From London rideshare to Cambridge. 1 h 35 min £6.