Is it possible this is another case of double counting? I mean, the wife not wishing to admit her husband was in prison? The birthplace and trade are the same, and Bilston was not yet as big a place as it was to become. Irish surnames, too, were rarer then than they were to become. The ages are admittedly different, but we're used to that on censuses, and other threads note the tendency to equalise the ages of couples on censuses when the bride was some way older. I only see one birth reg that fits - as Kilgallan in Wolverhampton district in 1850. Unless someone can find the two Martins on some other census, of course.