My first though would be to join in line with the upwind end of the runway - in other words, the same position from which you'd normally report "downwind".
But then my second thought is that if there is a reason for this, it's best to ask ATC. And if there isn't a reason, then ask (over the r/t) for a base join instead.
Then I had a third thought, which was that maybe an American style 45-degree join would comply with ATCs requirements, and would be quite neat? (It's worth pointing out, though, that the 45-degree join is actually illegal, since in the right hand circuit which ATC asked for it would involve a left turn. Still, this doesn't seem to bother the thousands of Americans who use it every day.)
I don't really know the answer, though. I'd be interested to hear the view of a controller at the airfield in question.
FFF
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