You almost caught me with the thought about the roof collapsing, but that would assume the internal brick walls, which are far from lightweight, would have been beamed out first, or they, or a big pile of debris, would be visible.

I don't know the detail of the roof build, but had a mental image from seeing past structures that they may simply be precast, reinforced concrete beams similar to door or window lintels. They'd have to be reinforced, or they'd simply break from their own weight across the span of the roof. The precast beams would be very quick to assemble and glue, bond or cement together, and each beam would be relatively easy to manage. A wooden or pitched roof would have been insecure, easy to break into to steal or acquire the contents of the building. Though we've noted earlier we don't know how tough the original doors might have been.

I've shoved the page up without the pics added yet, just so the positions of the adjacent pillboxes can be see relative to this building.

I've pondered this problem for a long time now... spent a lot of time going over all of Fox's pictures this afternoon, but I'm still no nearer a solution. I've never ever heard of a roof being built to accommodate water; who knows, maybe it would work (didn't the swimming pool help extinguish the fire in the movie "Towering Inferno"?), but i don't see it working to diminish an explosion.

i have no proopf at all, just a feeling, that this structure was not an armoury, bomb dump, or ammunition storage building. I just don't think it looks like any of these things. I feel this way because......

I don't know for sure either. We are going with the arms side of things in respect to guidance from those who may have been down this road before, but accept that this is no guarantee.

Now that the pillboxes have been added, I'm beginning to wonder if the building plus the wall is some sort of defensive structure, but I'm struggling to come up with a strategic or tactical use for the them, together with the pillboxes.

The problem, as before is that the usual airfield defences are fairly well documented, the various pillbox types and battle headquarters are well known in their various guises, so I think we're still open to proposals, hence the detailed description on the page, even though we have given it the store name.

Zute alors! Sacre Blue!!

Ze French getting the blame for zis controversy too?  Must have been a big airfield as one of the pillboxes eez, how you say,  near Toulouse.

I've dug (sorry) out the missing four Abbotsinch pillboxes to complete the listing of ten, and added these to the map, so the building's position can be seen in context with the perimeter defences.

I don't know if this adds to, or subtracts from, the arms store story, but it seems a bit short-sighted to store any arms in such a position.

In an attack scenario, this would be unannounced, so the airfield personnel would not have time to remove their weapons and ammunition from the store, a slow process given the small doors. Once an attack had begin, they would still not be able to get to the building without coming under fire, and the moment the perimeter was breached, the attacker would have won a handy source of weapons and ammunition with which to carry on the attack towards the control tower.

Oops, I think I just came down on the side of the "Nays" regarding the use of the building as an arms store

A contact at RCAHMS has consulted WWII photographs and confirms that the building and the bridge were both military structures constructed between 1941 and 1945.  The area was included within the boundary fence of the airfield at that time.  There was also a protected dispersal area nearby.

I wonder if this area could have been the repair yard?

I wondered if the bridge was from the time, good to get the confirmation. It had to be inside the perimeter (due to the pillboxes) but I wonder how far the perimeter extended on an airfield. The few field seen up north cover a lot of area, tens of yards past their pillboxes, but are also larger. The Black Cart makes an obvious line, but the rest is obliterated by later development.

Perhaps the error (if that's not too strong a word to use) has been the assumption that the W-shaped baffle wall is related to purely military - in the sense of weapons - use.

I'm guessing if the wall had been full of bullet or shell marks, you would have noticed, so it seems fair to assume it was not fired at regularly, or as a matter of course. I mention that only because the mention of repair made me think of the engineers working on the machine guns and cannons from the aircraft, which would have to have been test fired at some point. Having seen modern chain guns bench fired without ammo, you don't want to be too near that when it springs into action!

The building is clearly non-productive, in the sense that there is no natural lighting from windows. The doors are man-sized, so are not designed to allow anything large/wide to be moved through them, and there's a step on the twin doors at the wall, and both these, and the single door to the west are approached over soft ground, so nothing heavy.

Have you noticed that the Birds'eye view from the north was taken at an entirely different time of the year?

Indeedy, the Bird's Eye pics are also (usually) newer than the plain aerial view too, but I suppose that this will be a ongoing variable, as imagery is updated and revised by the providers.

There's a good side and a bad side to the fact that this is now a competing market for the imagery providers. Good is that they are forced to keep themselves competitive, and attract buyers for their pics, which means they need to keep getting out there and taking new ones - which we eventually get the (free) benefit of.

The downside is that the old ones are lost, so unless you taken downloads of every site you think you might be interested in, or that shows something old and useful, then when the images are updated by the provider... you're stuffed, because the old images are gone, and they're not coming back.

These are actually called tiles, simply because the big view you normally see is made by tiling lots of smaller images together seamlessly. I used to be able to get hands on the old tile sets from Google as it's possible (if you are programming the maps manually as SeSco does on its own pages) then you can also tell the code which tile set to use, but this information seems to have disappeared from the resource list, or there's now just so much programming info in the discussion group I just can't find it any longer.

I've programmed Virtual Earth too, and it basically works the same way, so I suspect the same trick could be done there too, but as I haven't needed the VE code (cos we use Google) I'm not 100% sure if that's correct, but it would be handy if it was.

I mention that only because the mention of repair made me think of the engineers working on the machine guns and cannons from the aircraft, which would have to have been test fired at some point.

Apollo, in my experience aircraft guns were test-fired on the ground only when the aircraft was being accepted by the airforce. When the aircraft-mounted weapons were fired they were fired into  regular butts and these butts were always located outdoors with lots of space for air circulation. The gun manufacturer of course would have tested some of the guns produced, but not all of them, and while this may have been done at an indoor butts, they would not have been fired in a bank as they would be when fired on an aircraft. This mysterious building remains a mystery.

A reassessment of the area by RCAHMS now suggests that earthworks at NS 46965 67258 were more likely to have been a bomb store.  The road proceeded from the known entrance over the bridge and then forked and entered the earthworks from both ends.  

I have observed that slight traces of a rectalinear shape are to be seen on Multimap particularly the Birds Eye view from the north.  The area has been scraped, probably after a recent flood as banks of debris have a lot of plastic debris embedded and then ploughed so the outline is not clear.  The area of rough unploughed land just over the bridge suggests to me that it might be related to remains also.

I wondered about the triangle of land that was avoided by the tractor. Why wouldn't the farmer just plough over it if it was sound? I had mentally assigned it a classification of "bog", fed by the channel the metal bridge crosses.

I don't know that the bomb store story works too well, for me at least, although I'm with the Fox in that the fact that the bridge is there suggest some relation of the land to the airfield

Bombs aren't exactly lightweight, even small ones, and the engineers didn't carry them one at a time, they would be on trolleys, sometimes even towed by small tractor units. Even during the war, placing a bomb store such that the route to it involved traversing a little narrow bridge seems needlessly hazardous. The simple span looks as if it would sink under any sustained use/weight.

Given that the site is so close to the runway, they'd have been as well siting a bomb store (if there was one there) on the nearer side of the channel - the difference of 10-20 yards if it blew up would be minimal.

I'm afraid I'd have to say that a bomb store would want to have been much further away, this spot is almost a real stone's throw from the runway, and a look at some of the other airfields shows this, some are so far away they're not even with the airfield perimeter, and look like unrelated building were it not for the records that identify them.

Mentioning records, it's funny that Abbotsinch, and airfield near Glasgow, doesn't have more detail documentation easily to hand.

With you on the mounted guns Duguld, calibration of sights would have to be done "in flight". My ramblings (and they were mere ramblings) on the W-baffle were more of safety thought based on working one the weapons when not mounted. Even though empty, one stray round from a machine-gun or cannon, not spotted by the engineers, could cause terrible damage if it were loosed locally, or somewhere far away if it were accidentally fired in the open and landed "miles away" as it were.

It's a pity there's no other supporting evidence, the vents are to small, there are no cable ducts, there is no engine room nearby (the base to the south is too lightweight), as the earthing straps still beg a realistic reason for their presences. If only there were other corroborating evidence on the site, we might be going back to some sort of radio installation. It does not correspond any of the radar of the time, and is just too small and insubstantial for any of the types known, either early or late.

I have read elsewhere of mystery buildings found on an airfield, and later classed as VHF transmitting stations used for direction finding, but they looked nothing like this.

Maybe it's time to wonder what other building lay around these airfields, and see if any of them tie in better?

Three questions:

1) Sorry! But if you're going to attract enquiries from Google and possible replies, you need 1) Ammunition  2) Abbotsinch. I know just how easy it is to type the wrong thing in and not to notice it, until you've sent off whatever it is, in the incorrect form. And then it's just too late.

2) Why would aircraft flying from Abbotsinch be carrying bombs?

3) Going back to my earlier suggestion, where is the bomb disposal hut at Abbotsinch located? This is not inconsistent with my second question in wartime conditions.

Passerby.

2) above.  Were planes not equipped with bombs to drop on U boats?  Mind you for bombs you could read torpedoes.

Re gun calibration, it is my understanding that in the case of fighters the guns had to be set so that the stream of shells/bullets met at a point a certain distance in front of the plane.  This was done on the ground by chocking the main undercarriage wheels and lifting the tail wheel off the ground until the plane was horizantal.   Rounds were test fired into butts which were high thick brick walls with a considerable bank of sand in front. After each test firing the gun alignment was tweaked until the desired result was acheived.  I suspect that guns in turrets were done similarly on the ground.

Guns were testfired in the air at the start of missions but only to check that the firing mechanism was operational.

Bristol Blenheim I bombers of No 62 Squadron RAF at Abbotsinch 1938 http://www.scran.ac.uk/database/record.php?usi=000-000-128-874-C

Abbotsinch was both RAF and latterly RNAS, HMS Sanderling, which did fly torpedo operations.

Question 1 - Er... That's not a question, it's a statement about something, but a bit to cryptic (for me anyway).

Question 2 - Bristol Blenheim I bombers of No 62 Squadron RAF at Abbotsinch 1938 http://www.scran.ac.uk/database/record.php?usi=000-000-128-874-C

Abbottsinch was both RAF and latterly RNAS, HMS Sanderling, which did fly torpedo operations.

Question 3 - There wasn't necessarily a bomb disposal hut at Abbotsinch - we just raised the description earlier as a possible use for this building, but it doesn't make much sense to try and do this in an enclosed building with no light, so it was, I think. dispensed with.

The Fox's gun calibration is along the lines of what I know about, and for non firearms-types I would add that the guns and sight ONLY agree at that calibrated point. At greater or lesser ranges the shells will strike high or low relative to that setting - this is where the pilot's skill and practice come into play. I forget the mix (I think it was about 1 in 4), but the tracer shells were important to let the pilot flying in the real world see where his shots were being laid, and he would adjust his aircraft's attitude accordingly.