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....TN-S appears outside, butt TT employed inside.

Good Evening Everybody (This is my first post)

Overview:
The supply to my parent's cottage consist of an overhead line of three individual cables. Originally, the supply drop from the final pole to the house also consisted of three cables (remnants of which remain in a seen in an attached photo).
In 1990, the three individual cables from the final pole into the house was replaced by a Split-Concentric cable. Looking at the cutout in the photo, there is a small piece of plastic which 'wobbles' (I know you shouldn't) over where (when I've seen other cutouts the same style) an Earth block is located, whether this cover is meant to simply meant to slide off or not I don't know, but the Consumer Unit is now in the way.
Prior to the new cable being installed the cutout was much further to the left, with the meter to the left of it with the tails from the meter running to a BS3036 CU.
Now, the old cutout was directly below the 3036 CU and after the current incoming cable and cutout (moved much further to the right) was installed I remember an Earth cable (probably 6mm2) dangling from the 3036 CU connected to nothing-although I'm sure there was a 'pinch' mark on it, therefore suggesting it had been connected to something, although far too short to connect to the new cutout should it have been.
My father claimed when the new cable was installed, he mentioned to the DNO people he himself installed an Earth electrode outside when the house was re-wired in the early 1980's, of which one of the DNO people mentioned not to worry about Earthing, as there was one 'on the poles running to the house'.
Anyway, for a few years this is how things remained (Yes I know, the house been without effective Earthing!!!).
Then we required three extra circuits to be installed and had the 3036 CU replaced with a Wylex MCB/RCD CU with 100mA T/D incomer and 30mA for sockets and outside circuits, (16th Edition applied at this time), with the earth rod (apparently not initially required as above) remaining and regarding the RCD protection in use as a TT system.
This how it is to the present day.
BUT the question has always bugged me 'Is this truly meant to be a TN-S system OR a TT system as is currently the present case.

I did enquire about this with photos on another site, but with no definite answer.
Some suggested 'Split-Phase' but I can tell you it is only a 2 bedroom cottage, no storage heaters (never).
Some say overhead TN-S supplies do not exist, but I have when reading on this site had seen people mentioning to have seen them, although a rarity.
If you look carefully at the rear transformer view, you can see a link between the middle and bottom conductors (N-E link?).
The transformer supplies three properties altogether, one set of three conductors leading to a nearby property, and another set of conductors leading to a pole which in turn supplies to other properties, including my parents.
On a side note, two properties fed from this transformer are right nearby, whilst the supply to my parents is a very long overhead supply (if this is actually a TN-S Earth, if a RF Circuit was protected by a 30A 3036 fuse as was originally the case, how long would it take to rupture and disconnect in an Earth fault with such a very long, thin overhead line?)
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Problems with uploading photos, could someone help please?
 
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