Ja Bird
From the EZY website
"Each passenger is usually permitted one standard piece of hand baggage to a maximum size limit of 55x40x20cm. There is no weight restriction, within reasonable limits - i.e. a passenger must be able to place the piece of luggage safely in the overhead storage bins without assistance. , In addition passengers may carry onboard a handbag, clutchbag, coats, umbrellas, duty-free goods, laptop computers, and small items of camera equipment"
If it’s a soft bag and over by 1cm then I’m sure you will be able to check it in as hand baggage
BA only allow this size when flying 1st/bussiness class