Richard J. wrote:
John Rowland wrote:
In Thames Rd aka Strand On The Green, just west of the railway bridge
is an alley called Post Office Alley which contains a small old
floodgate at the river end. Set into one wall of this alleyway is a
line of solid metal knobs which are shaped like carpentry dovetails.
The line is level (i.e. level with a spirit level rather than level
with the rather sloping ground). There is nothing in the other side
of the alley. I presume they serve some flood defence purpose but I
can't figure it out. Any clues?

I can't help with your question, but just to correct one point in
your post:
Thames Road is not "aka" Strand on the Green. The name Strand on the
Green is applied both to (a) the riverside village just downstream
from Kew Bridge, and (b) within that village the highway along the
river bank. That highway starts as a road but the road soon veers
away from the river at which point it becomes Thames Road. Strand on
the Green (the highway) continues along the river bank as a mere
towpath, but still has houses fronting on to it (with postal
addresses of xx Strand on the Green) whose land reaches back as far
as Thames Road, sometimes with separate buildings fronting on to
Thames Road.
Buildings or gates on the south side of Thames Road may therefore
carry either Thames Road numbers or Strand on the Green numbers,
usually without specifying which. As far as I remember, the
situation is not helped by the numbers on the two roads running in
different directions.
Finding house number X in Thames Road can be difficult!

"What is the name of this road" is often a surprisingly difficult question
to answer: it is not rare for the two sides of a road to have different
names, although this is a particularly unusual example, because there are
Thames Road properties on both sides of the road, and there are Strand On
The Green properties on both sides of the road, and the experience of
someone driving along the road is that both sides of the road are changing
name back and forth. In particular, there are some properties numbered as
Strand On The Green on the north side of the road east of the point where
Thames Road starts, which defeats your argument. Therefore I don't consider
my original post to be in need of correction.