There are 3 major agricultural treatises surviving and translated into English if you're really interested. The Dorking info comes from Roman historians writing on the invasion and then assorted sources recording life in Roman Britain e.g. the Vindolanda tablets, which among other things preserve an order for chickens and eggs for a dinner party for example. There's Greek sources even earlier (though not on the Dorking) - if memory serves correct, one of the last things Sokrates is supposed to have said was that he owed a cock to Asklepios and wanted Plato to pay it for him.The Romans wrote about them apparently. Fascinating.