Found Among My Mother's Papers

A tiny card, less than one inch by two. But thick
and sturdy (a whole generation, a world in that sturdiness).
In clear black print on a battered cream background, the following:

Arrow points to your CORRECT weight
ONLY IF you stand still on platform until
red hand stops before dropping coin.

And the purple-stamped date: 13 APR which, as it happens, is today's date
how long (half a century?) later. To the right of this --
below the bold printed Stones Pounds -- a purple arrow points
to the inch-tape figures, in between 2-6 and 2-7.
And below this, in bigger bolder letters:

THE BRITISH AUTOMATIC Company, Ltd.,
14 APPOLD STREET, LONDON, E.C. 2.

O city of my birth, where was she coming from, or going,
what was on her mind -- a taxi, afternoon tea, joys
or worries of an unmarried mother, far from her own birth
in Belfast, her girlhood in Burnham on Sea with its mud
and clownish lighthouse on stilts --

was I pestering her, did she need a pause
in the rhythm of her walking, what made her she stop
in the quietness or busyness of a London street to weigh
something (a three-year-old me presumably)
and slip this card in her handbag -- evidence for the jury

who weighs it now standing on the floor, the platform
of her cleared-out bedroom where he waits
for the red hand, the arrow to stop quivering.