My wife’s great aunt* was born and raised in Sutton Coldfield. Growing up between the wars she and her siblings saw Sutton grow and change a great deal, eventually becoming officially part of Birmingham in the 1970s. The last letter she wrote to us when we lived in Erdington was, as was all of her correspondence, addressed to “…Johnson Road, Erdington, Nr. Birmingham”.
*Watch out for autocorrect on that one.
Where is the sign shown in the picture. I always understood the border to be the other side of the Chester Road just by the (now disused) toilets in Wylde Green, which used to be where the Birmingham Trams terminated.
Knipersley Road on the Erdington Side https://www.google.co.uk/maps/preview#!q=Knipersley+Road%2C+Birmingham&data=!4m15!2m14!1m13!1s0x4870a4df5ff70225%3A0xcbf3dcbc10366964!3m8!1m3!1d1074!2d-1.8338721!3d52.5346899!3m2!1i1280!2i680!4f13.1!4m2!3d52.5347658!4d-1.8338416