wRoland Perry wrote:
In message , at 21:41:10 on Tue, 10
Sep 2019, Marland remarked:
It was London Transport which recalculated its route measurements to
Kilometres back in 1972 .
Ironically they chose Ongar as the 0 datum

I think they chose Ongar because it was the furthest east.

which means their measurements start on a line that was closed and is
now no longer theirs

It's not the only disappeared datum. Road miles from London were
measured from the Post Office near St Pauls (the tube station used to be
called "Post Office") because postage was originally calculated by the
mile.

Hmm, I always thought it was where the original Charing Cross was
located.

I could see the Post Office might have used its own datum for
postage from its own main London premises for its own purposes but
the Post Office premises you mention were not constructed until the
early 19th Century and many milestones would have been put in place
before that by the Turnpike Trusts who were required to do so.

The date of the building on that site today isn't relevant. Some say the
datum is actually a little further north, at the site now occupied by
Mount Pleasant sorting office; but that doesn't change the basic
principle.

Perhaps someone else can adjudicate.

The wording on this plaque seems pretty definitive

https://ads9rca.wordpress.com/2016/1...tarting-point/

Unfortunately, the plaque doesn't say 'Measured by... whom".

And the elephant in the room is that Charing Cross was the *penultimate*
stop on the trip in question ("a little village near Westminster" in
longer versions of the story), the final destination being Westminster.

If there had been a "final" cross at Westminster (and many people think
Big Ben is where distances are measured from) then it would be far more
compelling.

Quite a few people say that the Charing Cross (or Trafalgar Square in
fact) was chosen as a datum by the AA, as more central of a place in
London bearing in mind how it had developed by the time they started
publishing their own maps.

So the real answer is that nobody seems to know which one it should be and
one claim is no better or worse than the other.

You are making the assumption that one or other is "correct" and the
other must therefore be "wrong".

Where did I say that one or the other is is correct and the other wrong ?

All I asked for was an answer and it appears that there are several all
which of which could be correct for one purpose but not another.

Its almost as if you are wanting me to argue that your suggestion was wrong
so you you can start one of your long winded arguments to bolster your
ego even though I haven’t actually disagreed with you, just not accepted
that the one you put forward has any more merit to be the main one than any
other.

GH