Been puzzling me for awhile now.

The first bike I ever owned when I was 12 years old was a 1972 DT125 UK model.   When I got it, it was about 5 years old and without  lights or instruments.  The tank has been painted crudely with the stars and stripes motif like something Peter Fonda would be riding.
When dad started rubbing down the tank for respraying, it was found that the original paint was a kind of turquoise blue.

I would have naturally thought it to have been a AT2 as it was in that style of bike, but the puzzling bit, now I know a little bit more about them is the fact that AT2s have electric start whereas my bike did not.  It had a standard magneto / points setup and the same flat generator cover as the CT3 setup with yamaha embossed along the full length, half on the generator case and half on the sprocket chamber case.

Definitely a 125 as it had 125 torque induction badges on the oil tank and I can distinctly remember "123cc" on the cylinder barrel. The exhaust was a single unit without end can and had a stubby exit where the battles fitted, just behind the riders leg.

Anyone shed any light as to what it actually was?

Not a direct answer to your question, but I'm not sure that we got any Yamaha trail/enduro bikes in the UK until 1973 at the earliest. Maybe a bike that a serviceman had brought back from Germany?

As far as I know, only the US (maybe North America?) was the only region that did not get a choice of electric start or kick start 125 before the monoshock.  For some reason, 99.9% of the online parts diagrams are for the US models. 

You likely had a UK model AT2....  some info is in the Tech Library VIN tables...  UK Haynes manual seems have the most info that I know of.

 




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Alan beat me to the punch yet again...  and I sort of misspoke...  It would have been a DT125 model like you said but with an AT2 VIN prefix.  From what I've gathered, the stamped VIN would have been bracketed by * and it seems Europe and the UK had the same importer in the very early days?

DT125E model would have been the electric start similar to US models and all the parts diagrams... a  "E" suffix was used for "electric leg" or "electric start" in other countries and an "F" suffix was used for "foot start" or "kick start only".  Not to be confused with the US E and F models which were the 78 and 79 monoshocks (MX in the UK)

You may be right.  Since the bike did not have a registration document, all we had for identification purposes was the sales receipt which may or may not have had the correct year on it.
I can remember dad buying parts by quoting the frame number, but I cannot ever recall him ever questioning the dealer about the year of manufacture.

Haynes manual..  I remember we had one and it has a pic of a bike with the same paint colour as mine had originally.  Had a look for the image.

Still waking up...  one more bit of useless trivia is the US didn't get the "DTXXX" designations (where the XXX is the nominal engine size) until the 1974 model year. 

Up until 1974 our Enduro models used the Yamaha letter-number code system they started in the 1960's... by the late 1960's, first letter usually indicated the nominal engine size...  second letter the "type" of bike and subsequent letters/numbers often indicated features the version/revision number. 

A= 125
T= Trail (S was commonly used for "Street")
2= version 2 (preceded by versions 1a, 1b, and 1c in the USA)

(In the earlier years, the first letter was the frame type with "Y" indicating a conventional fuel tank in front of the rider and an "M" designating a "step through" frame with fuel tank under the seat...  this extra letter stopped when the step through frame models were more or less phased out...  in the early 60's Yamaha sold a lot of little "M" models... perhaps to compete with the venerable Honda "step through" trail bikes?)

"Haynes manual..  I remember we had one and it has a pic of a bike with the same paint colour as mine had originally.  Had a look for the image"

That's 1973 model paint scheme.

Possibly a handful of kickstart only bikes sold here and in Europe.

If my memory serves me correctly (which is NOT guaranteed!), I have seen the occasional UK model AT3 and CT3 advertised on fleabay. The Haynes guide, or Yamaha literature, might indicate whether or not they were marketed here as DT125 and DT175 respectively. I have a feeling that there might me a UK based DT forum so, if there is, then someone there might know.

And there we have it.  It was a Yamaha AT3 all along.  Great detective work, solving a 40 odd year old puzzle.  You guys rock!  
I seem to remember the paint being more turquoise than the blue in that pic though.

Good photo find!

No bulge in the left case for the electric start gubbins, so kick only.

Indicators might be off a later model, although possible that UK/Euro bikes got fitted with those "sunflower" type.

Seat definitely looks UK/Euro or Japanese - definitely not US!