Aer Lingus has a section on overweight fee, but it lists it as a flat fee. Perhaps there is some mistake on either page.

Excess baggage fees: Longhaul flights - all bags over 23kg-32kgs (50lbs-70lbs)

75 euros, or
65 British Pounds, or
100 US Dollars

Aer Lingus has a section on overweight fee, but it lists it as a flat fee. Perhaps there is some mistake on either page.

Excess baggage fees: Longhaul flights - all bags over 23kg-32kgs (50lbs-70lbs)

75 euros, or
65 British Pounds, or
100 US Dollars 

Shorthaul flights - per kg over allowance (airport only)
15 euros, or
12 British Pounds,or

• US Dollars (Unexplained - possibly: invalid on short-haul flight)