The Carry Freedom City Trailer. Pretty cool portable trailer [a tad tautological? – Ed] which you can use as a suitcase, folding bike holder etc etc. £245.00 but neat nonetheless.
The 12″ wheels glide over obstacles like stairs or kerbs, while the trolley wheels mounted on the frame allow the City to slip sideways through narrow gaps like turnstiles. Strap your folding bike on top of the frame whilst carrying luggage in the bag. The handle folds for quick stowage, and on longer journeys the courier bag can be detached and the frame folded.