There's another interesting feature at.

http://www.flashearth.com/?lat=50.206634&lon=-5.299558&z=19&r=0&src=msa 

I did site investigations on the playing field of the new Trevithick Primary School, and we turned up some interesting lode structures.
Now, Isn't the feature at the south end of the playing field, and the one you marked on the Flash Earth image part of Wheal Nancy? I believe the shaft in the field to the SW is also included in that sett.

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Seems to have been called two different names?

http://www.mindat.org/loc-37420.html 

Hamilton Jenkin says it was known as Wheal Nancy in 1792 (Mindat's info is a bit stale). It was later known as West Stray Parc.
I picked up a nice piece of calcedony off the surface when trench logging in the fields. The dump however was barren. We hit a decomposed elvan dyke in one trench, which contained very small, 2mm, double terminated quartz crystals, and this was associated with another feature containing angular quartz fragments cemented together with haematite. I had a small piece sliced and polished.
other than that, the site was bereft of minerals and we didn't find any signs of the ground having been disturbed in the past.
Investigations at the old Trevithick Primary School threw up a series of small tunnels running all over the site, no more tan 1.5 metres below the surface. They were only big enough to crawl down and it was suggested they were to convey water. I noticed no sign of any silting or any hint of water having passed along them. Tunnels of this type are not unusual in the Camborne Redruth ditrict.

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other than that, the site was bereft of minerals and we didn't find any signs of the ground having been disturbed in the past.

I suppose that situation is unusual for the area concerned?

Small unrecorded tunnels with no 'apparent' purpose are always intriguing.;D

Well, in answer to my own question, it appears that there isn't an adit at the bottom of my garden. The coring report shows that three of the 14 cores done in my garden found a lode, and a tunnel, 6-8 foot wide, and about 30 feet below the surface. The 'water scouring' is from a street gulley overflow that SWW water had put in. Oh well. ::)

Does the report refer to 'coring' and 'cores', or are they bore holes drilled by the rotary percussion method?

There is a usual way that investigations are undertaken, occasionally you bump into some firm from up the line doing something completely different. If it was a coring investigation, I'd be interested in eyeballing the report, as it's always interesting to see how different people skin a cat. I've seen a few cores thrown away here and there and wondered what they were the result of. Some of them polish up quite nicely.

The report doesn't indicate the nature of the investigation, other than to use the terms 'cores', Tony, and there is a table for each run outlining the type of formation found. They left no outward signs of having disturbed the lawn through-which they would have cored.

Any good driller caps their bore holes. They only tend not to when the whole place is about to be obliterated.

Cores are cores, so if they say cores, they cored it.

Interesting.

coring? wow - thats a lot of work (and expense) for a site investigation! Its a superb way of doing though.