Friend of mine has just pointed out the Lat/Long of the crane that was published in the Notam. Not sure how accurate Google Earth is, but 5129N 00007W seems to be about half a mile to the East, just on the Western edge of The Oval cricket ground.....I could be mistaken.
Mind you, the Notam does say "Within 1nm of" the above position...
Yes. Using notamdecoder.com that position, from the Q line, resolves to the grounds of Ibberton House which is most of the way to the Clapham Road and 800m from the crane (over 3000' from centre of river?).
However, as you point out, the NOTAM states WI 1NM, and this is reflected in the 2nm diameter circle displayed for this notice on notaminfo.com.
Two interesting small discrepancies emerge though.
1. The notaminfo.com map displays the location at a more accurate position within 150m of the crane and a similar distance from the river.
2. The NOTAM E line shows seconds figures in the position information and resolves to Pascal St outside Covent House which is 600m from the crane and the same, about 2000', from the centre of the river.
"... and offers no analysis."