Property prices have come on a bit since 1086.  Way back then Islington as a whole had a taxable value of 2 geld and comprised 27 households, both quite high for the time apparently.  There was also land for about 2.5 ploughs and Islington was firmly in the Hundred of Ossulstone. You can have a look for yourself on the wonderful, easy to use online version of the Domesday Book by my friend Anna.