There were hundreds of thousands of Irish born immigrants living in England in 1851. There is a 2% sample of this census available online, and the "strays" not living in their place of birth have been separated and indexed for most English counties, with Irish and Scottish strays listed separately. If you go to the following website, and search for surname, you get the estimated date of birth, place of birth. Unfortunately, most entries were merely recorded as Ireland, some gave the county as well, but a few give the town also. It is worth a look, but remember that it is only a tiny fraction of those living in England at that time. http://web.ukonline.co.uk/sheila.jones/ire.m.htm