let's try some more specific coordinates.....perhaps that 'dean' book is key....go figure:

...and let me see...a rough guess....under the moby dick plaque, evans?

oh wait a minute...that looks more likely...to the right of the above....LOL....go figure:

https://www.google.com/maps/place/51%C2%B030'25.9%22N+0%C2%B007'28.3%22W/@51.5070532,-0.1240366,3a,15y,39.82h,88.07t/data=!3m6!1e1!3m4!1swYkmD9kkK5doLQL1QrnE4A!2e0!7i13312!8i6656!4m5!3m4!1s0x0:0x0!8m2!3d51.5072!4d-0.1245184

let's 'jump in' then and see what the blue circles are all about...and it's charing cross....as it goes, eh?