'Elephantine'.

That could be it, Douglas. The phrase 'middle eight' is hovering somewhere. Middle eight what? Bars?

Nonetheless, Bazza, she had her admirers, and not just John le Mesurier.

Indeed so, John. She even moved her fancy piece into the marital home. Still & all, I am an admirer. The matron of matrons.

middle eight and bridge
 

John,
I just did a web search, and we both are right. Under the Wikipedia article "thirty-two-bar form", both "middle eight" and "bridge" are described; and essentially mean the same thing. It seems that this technique became popular about 1925, and literally thousands of popular songs have used this structure since.
So, I guess that it sounds natural to our ears now. Oddly, I have not seen it mentioned in any of the eight or ten textbooks books on prosody which I've read. But, in a little book on how to write a pop lyric that I bought at a second hand shop, a whole chapter is devoted to it.
It does juice up your poem, by the way.

Thank you, Douglas. May I recommend ... ah, I can't find it. It is a book about the art of the great songwriters, Cole Porter etc, from the 1920s to the 1950s. I have found it very useful. I will put it up here when I do find it. It will be useful to all those poets who write the sort of stuff we do.

The name of it is 'The Poets of Tin Pan Alley' and it was written by Philip Furia.

Fashion demands that human forms
Be, like some lattes, skinny;
Not many dare to flout such norms
So Fatty yields to Thinny.

High time to break the media spell,
This curse of weight reduction,
To let the fuller figure swell
Unscarred by liposuction!

The Michelin man -that bouyant air
And sensuous rolls of rubber! -
Should make both sexes well aware
Of beauty born from blubber.

Cat-walk designers, start afresh,
Dump models looking willowy
For those with Rubensworthy flesh
Plump, succulent and billowy!

Regarding all sins of the flesh I’ve a theory --
While friends may regret their own blubber’s deployment
the truth is beyond any possible query.
The greater one’s flesh then the more one’s enjoyment.

Exponential’s the word to describe my joy’s curve
at the sins of the flesh which I’ve tested and tasted;
and the corpulent verve of my unrestrained lurve
simply proves that such sins are much better unwaisted.

God made me a lard-butt -- a matter for joy!
My poor sinful flesh will not care to or dare to
attempt to deny that I’m proud to deploy
the heightened delight that my more flesh is heir to.

And when at the Crem I seek final release
I’ll burn so much better well larded with grease,
while pitying friends who, with less of a skinful
of fat, found the same sins less fleshfully sinful.

(Not exactly on topic, but what the hell?)

You call me fat? You puny sprat!
Without this coat of blubber
I’d surely freeze in icy seas,
You skeletal landlubber!

You’re skin and bone, a thing like Jonah -
Indigestible.
The little krill I slurp and swill,
Are more comestible.

I plumb the deep where lobsters creep,
My massive lungs inflated,
And when I sing, the oceans ring
With music unabated.

Your little boat may help you float,
The breeze may drive your sail;
But when I blow, why, then you’ll know
The power of a whale.

John,
I found a used copy of Mr. Furia's book on a internet book megasite for $1.00, plus $3.00 postage. This was a big saving over the gas I would need for a 75 to 100 mile roundtrip to a college library.
Anyway, it arrived yesterday, and I was up until the wee hours reading it. It's a good piece of scholarship, and a fun read. Plus, now I am getting to know why those songs that I listened to (50 years ago) on my mother's old 78 records sounded so great.
Thanks for the tip.