That figure is misleading, although in a way that further demonstrates the differences I guess. The main maternity hospitals for most parts of Wales close to the border are in England; e.g. most families in Flintshire have their children in Chester, most in Mid Wales in Shrewsbury, etc.
I don't know much about how English settlers vote but in Scotland of all minority groups polled (Scottish Asians and Europeans are usually large enough to be polled accurately) on party voting and even to an extent on constitutional matters they vote more in line with Scots. English voters in Scotland tend to be entrenched in their 'native' patterns.