RSPB Limited Prints

I've been given two RSPB limited edition prints to sell for a charity. I don't know anything about them or their value, but the person I got them from said they should be worth around £70. They are both prints out of an edition of 500 by Gillies Campbell. Short-Eared Owl from 1980/81 and Osprey from 1983. Any more information is well appreciated (including where I could sell them). PS: Glass in frame of Short-Eared Owl is broken but picture unharmed.