Flypastpastfast's point about extra luggage is spot on.
I've looked up Easy's carriers regs and found this.....
In addition, passengers may carry on board a handbag, clutchbag, coat, umbrella, duty-free goods (small items), a laptop computer, car seats for infant passengers (see "infants and unaccompanied minors" below) and small items of photographic or scientific equipment. These will not form part of the above allowances.
I suppose that the BAA have the final decision and 'security' is a blanket coverall.
I wonder what would happen if you arrived with one of each of the above, as it doesn't say OR anywhere in the sentence