The Stone.

The stone is a narrow slab, flattish on the Cross-side, but irregular on the Symbol-side. A big break runs diagonally from the RH top to about midway LH, and there is no way of knowing when this chunk came off, but there are, or were a beast with a curly tail, sitting above a serpent, and touching the bottom of the serpent's tail a partially buried mirror, all down the raised RH side. Perhaps they will excavate around this area if they do decide to move the stone, to see if there is a fragment with other symbols on it.
This stone is regarded as a re-used Class I stone, but it might just as easily be a Class II with the Pictish symbols squeezed onto the back of the (to the sculptor) more important Cross. Either that, or other symbols once occupied the other, (I would imagine) easier side to carve.
The symbols are incised, and the Cross side is in low relief.
The stone currently stands beside a woodland path on the hill South and East of the village of Glamis, called Hunter's Hill. It has a low iron fence around it, and I read somewhere that this is a handicap to photography, but there is precious little visible left to make a decent photo anyway. The Cross side (facing South) is particularly badly obscured by frondy mosses and lichens, while the Symbol side is merely weathered. The Cross side is so badly spoiled, I think, because the intricate carving has given the elements more, and smaller, surfaces to work on. Judging by the photo of the stone in ECMS, it has deteriorated quite badly in the 100 years or so since the photo was taken.
It prompted me, once again, to wonder about how stones that were photographed and recorded, not drawn or painted and subject to an artist's perceptions and preferences, just a hundred years ago, could be so badly weathered in that time. I am no geologist, but perhaps someone who has some knowledge of the subject can explain. Does it take a long time for stone to destabilize, and then it disintegrates quickly once it's softened? The alternative might be that they were sheltered somehow, until relatively recently.

It is one of the stones that cry out for conservation, but raise the ethical question of whether to "curate" them for future generations, or let them fade away naturally, as they have obviously outlived their original purpose, since no-one has seen fit to maintain them, or replace them, for most of the 1200 or more years they have possibly been standing, until now.
The counter-argument is that they are too precious, and rare, connexions to a segment of the history of Scotland to allow them to disintegrate uncared-for. But. They are not convenient for the modern tourist nor the landowners who do not wish to be bothered with sight-seers, both of which are valid points. With expansion of arable farming generally, and the mass draining of huge unused tracts of the landscape, many of the stones have come within fields that never existed before. The many fragments and damaged stones that have been ploughed up already bear witness to this.
Unfortunately, I can see both sides of the argument. Perhaps the compromise is that we put copies in museums, where you are not allowed to touch them, anyway, and nobody is going to be any the wiser ( besides, they are full of illustrations and reconstructions and other fakery anyway), and leave the stones to melt away in their original positions. As long as they are faithfully reproduced at this stage of their deterioration, they will be as good as real, for scholars, and handier for the casually interested.
[There is an excellent example of this approach at the Meffan Institute, Forfar, by the way.]

If you are visiting the stone, take the path that immediately faces you. There is a barrier, so you can't take your car up, but it is a pleasant walk up from the village, which has a heritage museum, and the famous big Glamis II Stone in the Manse garden. There are three fragments of other stones in the Kirk as well, although two aren't seen as Pictish stones.There are also toilets (which were open in the Winter, I was surprised and pleased to see) just down from the car park. Walk out the easterly road from the village square, towards the Forfar Road, and about 30 yards diagonally across it there is an unmarked opening in the woodland. Be wary. Although it looks rural, it is a busy and fast stretch of road, and the entrance isn't far from a corner. The stone isn't far up the trail, and sits to the left of it, quite easily seen.
There is talk of putting this stone in the Kirk for safekeeping, and I think conservation and shelter is the only way this stone has any value for the future.
It might be worth combining a series of visits to stones in this area, or take this stone in while attending some of the events at Glamis Castle, or some such, because frankly it isn't worth a special visit as it is. If it is cleaned, it would be a different story.

The Cross.

The Cross is comprised of four roughly equal-sized arms, notched at the armpits, standing on a "base" which is similar to the bottom panel of the cross itself. The centre of the arms is a disc of a kind of key-pattern, still visible.
The topmost panel is interlace work that has a St Andrew's Cross through its middle, above a criss-cross interlace. The right and left arms each have two cresecent-shaped interlace works on the outer 2/3rds and a rough bit of knotwork on the inner 1/3rd to fill the space and resolve the laces of the main design. The bottom panel is none-too-clear but apparently is some kind of knotwork. Ditto the "base".
The top left space behind the cross has an angel with the scrolled armpits where the upper and lower wings join. A similar, but better carved version appears on the equivalent panel of the Eassie Stone, just a few miles along the Meigle Road (same road, opposite direction. [A94] ).
The top RH Panel has a pair of fighting men? The LH corner has been broken off and the figure has been snapped off at the knees, but enough of the arms survive to suggest that he is grasping the wrist of his bird-headed opponent, and that they are a version of the fighting pair on the Glamis II Stone. (The diagonal spear with a ball-end, the holding the wrist, and the RH man's axe all seem to be there, but unfortunately, the panel was too moss-covered to do a proper search. I am relying here on the photo in ECMS.)
The lower left panel (it all seems to be one section) has a deer, another deer below that, an indistinct patch, and something in a rectangular frame which is not very distinct. I'm not too certain about the last bit.

The RH side has two beasts, running, but with their tails looped through their back legs. They look dog-like, but they have three claws per paw.
Below this again a Triple Disc, with slightly squashed "handles", and a "Flower" which is buried these days. The "Flower" is reputed to have only one bloom, instead of three.

The Symbols.

The main body of the Serpent on the reverse is still quite clear, but the head isn't. The Beast that once showed quite well above the snake is reduced so badly that I thought it might be the Goose symbol, with its feet erased ( ###), although I spotted the hole in the tail (####) and thought it was the centre for another symbol.
This misinterpretation underlines the hazards of observing a stone without consulting the references beforehand. Sometimes it helps to know what to look for, and sometimes you only see what you are expecting to see. In this case, comparing my sketches and notes with the earlier photo showed where I had gone wrong. On the other hand, it provided a nice illustration of just those hazards.

Similarly, the disc of the Mirror symbol which hangs from the Serpent's tail is faded so badly and seems to join into what must be a natural feature of the rock ie two parallel fissures, that I took it to be (#####). Yet again, when I compared notes with the photo, I could see (####) which is obviously part of a mirror.

N.B.

The Meffan Institute in Forfar has an audio-visual display of Standing Stones, which deviates from the standard designations of the stones, and this worth bearing in mind if you visit it.

Following the standard practice, the stones are as follows:-

Glamis I is the stone on Hunter's Hill.
Glamis II is the main Cross Stone in the Manse Garden at Glamis.
Glamis III is a fragment of cross-slab (not regarded as Pictish)
Glamis IV is a fragment with supposed Triple Oval on it, now in Glamis Kirk.

Following the designations in the Meffan Institute they are:-

Glamis I is the one in the Manse Garden (II above).
Glamis II is the fragment of the top of a cross-slab found in 1967.
Glamis III is the fragment of cross-slab (III above).
Glamis IV is the fragment with Triple Oval (IV above)
The traditional Glamis I has been redesignated "Thornton".

I can see why someone would feel inclined to tidy things up, but there is already a tradition, and a considerable body of literature using that tradition, and this re-labelling just causes confusion for no gain. Why the stone found in 1967 wasn't just called "Glamis V", I don't know.