To be honest Tom, I don't think we can ever be sure.
The examples we have are such a mixture of parts with either plain top cap or No 20 Top caps. My example has the base part / rod connection of a No 3 and the top cap of a No 20. The grenade in post #1 has the base part of a No 20 and a plain top cap. Neither is marked anywhere as a No 11 Mk I or a No 3 Mk III. But maybe they were marked on the wooden crate.
My conclusion is that whatever the parts, whatever the rod length these grenades were built to supply users of the MLE rifle, so they should be classed as No 11 grenades. After all the No 2 was originally supplied with a short 10 inch rod for the MLE, said to allow firing from the shoulder.
You state "The Specification to govern Manufacture and Inspection, together with the associated inspection drawings, defined the markings to be stamped or stenciled. With or without a body plug stamped No.11, the issue of whether other grenade type numbers might have been used is just speculation".
I agree and it is just speculation that they were ordered as No 3 Mk I* or No 11 or Mk I or No 3 Mk III. We simply don't know and the key issue is that the fact that the specifications beyond No 3 Mk I state 'for the short rifle' whereas the No II Grenade specification is for the 'Long Rifle'. Now we can consider that Rifle Grenades were needed for the Long Rifle as well as the short rifle, indeed the move to the No 20 without the Muzzle clip pretty well confirms that all rodded grenades would be used from a static position, whereas use of the clip allowed the soldier to carry the grenade whilst on the move.
Regarding all of the examples we have, they are all to some extent hybrid and 100 years later we have no idea if an individual grenade was manufactured as a hybrid or modified post production. We also don't know if the rods fitted were factory fitted or changed in the field to suit operational conditions (range to German trenches). Can we base it solely on rod length, maybe, but who can say 100 years later whether all the rods are original?
So regarding your question, I would with hesitation state that the grenade in post #I and my grenade and Dave's grenades are all No 11's purely on the basis that to remove the muzzle clip was first and foremost done for the MLE long rifle. It was only with the coming of the No 20 that the clip was always omitted, basically stating that rifle grenades would be fired from a static position.
If anywhere in WW1 grenades there is a grey area it's the existence of the No 11 and some of the written specs for the No 3. As we don't know the dates of introduction or date it was declared obsolete, we can't be dogmatic about it and I'm quite sure most people are not bothered about it being a bit vague. All part of the fog of war.
I think overall we may just have to differ on this but one day maybe we can share a pint and discuss it at length.
As Donald Rumsfeld said
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones"
