No - just the initial (ie first) letters. I think.

Leave your lavish,
Expensive ways.
Squandering twits are
Scorned these days.
Infamy waits on
Such excess:
More is less.
Over-consumption
Reaps no laurel.
Ample feels good, but
Less is moral.

Then why does every example so far have a last line that begins and ends with the same letter?

The last line must start with the last letter of the last line because the poem is an acrostic of the last line.

Thanks Jerome. I hadn't noticed but thanks to you I have now.

Neat and pointed, Susan.

Roger, I think it's just a coincidence.

I've been looking at all my efforts so far. The last line has to begin with the same letter as the first line, and since it must also be an exact replica of all the left-hand initial letters, it has to end with the same letter as that downward list so...Roger is right.

But I think that is a result of the form rather than a necessary fons et origo for the poem.

My brain hurts.

Imagine what my brain feels like. I don't even know what a fons et origo is.

I just brought up the letter thing because I was halfway through a poem I was writing before I realized it wouldn't work, so I thought I'd spare others the same fate.

Anyway, here's all I've eked out so far. It needs work (and by "work" I mean "throwing out"):

Why Not Now?

Will you ever
Have the time?
You are never
Near and I'm
On my knees
To beg you please
Not to squeeze
Out of your vow.
Why not now?

Roger, I think the fact that the three examples here have a last line with the initial and final letters the same is just one of those scary coincidences. The rubric simply stipulates 16 lines max and that the left-hand initial letters of the piece spell out the last line.

In the 14 winning entries in the two previous Spectator panacrostic comps linked to in this thread only one of the spelled out lines (initial lines in this case) has intial and final letters the same. ( 'Sarah Palin's specs'.)

If Susan's ingenious twelve lines (sorry Susan) had ended

Reaps no maizes
Ample feels good, but
Less wins praises.

she would still have complied with the instructions.

Oops, you're right. Having just tried one with mismatched bookends, I've realized it's impossible any other way.

Sorry, Roger, you and Ann were right and I was wrong. However, as Ann says, it follows automatically that the last line begins and ends with the same lettter because of the acrostic so no more effort is involved. And, of course, my amendment to Susan's piece would have completely wrecked it.