In article , Set Square
writes
In an earlier contribution to this discussion,
Kalico wrote:

[snip]

something like this ?
http://www.screwfix.com/app/sfd/cat/...18649&ts=48872

Indeed

I looked at some of those in one of the sheds. They would do at a push, but
are really too large in diameter relative to the central hole - pushing the
hole in the worktop too far out from the corner. I reaaly want a smaller
flange than this.

How about a pipe stiffener for mdpe in white nylon as is has the through
hole sleeving and a small diameter flange to finish the top surface. I've got
one for 25mm here which is a bit too small (20o/d, 17i/d), but one for
32mm pipe would prob do the job (guess 27o/d, 24i/d?). Plumbers'
merchant will prob have one offs. Doesn't meet your chrome finish spec,
but you could place a bright plated or stainless washer under the flange.
I've tried it here & it looks ok but is actually less obtrusive without the
washer. Or do some mfrs make their stiffeners in Ali?

Hope you can visualise the idea.
--
fred