Okay. Lincoln is the Cointy Town ('capital') town of the Countu of Lincolnshire, so that's cleared that up. I thought of some other information for you. 'Code' , according to something I read somewhere is a Celtic word meaning 'Cobbler's glue. So Code appears to be a 'trade name', like Smith, Thatcher, Cooper, Fowler, Butcher, etc. Codes were probably, originally, makers of cobler's glue! So were probably 'freemen' and not serfs in medieval times. The name, I aslo read somewhere, might also be Anglo-Saxon (old English) rather than Celtic.
Ireland was for about 500 years 'colonised' by English people. Most of the aristocracy of Ireland, for instance, were Norman-English - not native Irish, and large numbers of British people were settled there over those years. N Ireland, of course, was settled by Scots - hence the present Presbetarian (not Catholic) majority in N Ireland. So, Codes might have originally been of Anglo-Saxon stock, settled in Ireland, and became 'Irish'. All speculation of course!