Ordnance Survey Map of <a href="https://en.wikipedia.org/wiki/Blake_Hall_tube_station" class="extiw" title="w:Blake Hall tube station">Blake Hall station</a>, Essex.
Unknown author<span style="display: none;">Unknown author</span>
Ordnance Survey, Essex nLXI.NE. Original Scale 1:10560 or Six Inches to One Mile.