Taken from Luton Airport Website...
Important Passenger Information - Hand Baggage
We would like to advise passengers that
there have been no changes to restrictions on hand luggage at London Luton Airport and the following still apply
- STRICTLY ONE PIECE OF HAND BAGGAGE PER PASSENGER
- LAP TOP COMPUTERS COUNT AS ONE PIECE OF HAND BAGGAGE AND SHOULD BE REMOVED FROM CASE PRIOR TO SCREENING
- LIQUIDS LIMITED IN QUANTITY TO 100 ML TO BE CARRIED IN A RESEALABLE PLASTIC BAG