Thanks !
Andy, square, or rectangular, were probably the norm, but it would depend on the actual area of the concrete being laid and, to an extent, the shape of the hard areas; for example, a "frying pan" dispersal, or a "loop"( or "spectacle") dispersal.
The format could also probably be dictated by the methods used by individual contractors who actually built the airfields, the main two being McAlpine and Laing, and also the region or area where the fields were built, and the source of the raw material.
As an engineer, you will know, far more than I would, that the ground that a structure is built upon, can dictate the type and composition of the materials used, and, to some extent, the way / shape these are laid down, which is also noticed in the differing colours of such hard-standings, depending on where in the UK they were built at that time, and where the sand, stone, cement etc came from.
A "straight" paved area, such as the main "roads" of a "loop"(or "spectacle") dispersal, or a larger "apron", would more often be uniform, with either square or rectangular "slabs", again depending on the construction method, often down to the size of the shuttering used when pouring the concrete.
Also, bearing in mind that these airfields were only designed for use "for the duration" ( of the war ). to use a term then in use,, if it was good enough, then it would be good enough.
However, the "powers that be" who oversaw such things, at least had the foresight to design the "pans" in such a way that the slabs should be offset, where required, rather than a geometric perfect layout, in order to allow for any movement and / or "crumbling" between the joints of each slab, thereby minimising the overall "decay" of relatively hastily-built hard areas.
If, for example, a large "apron" type of area had to be laid, such as the post-war example at Duxford, then yes, this would mainly be square or rectangular slabs overall, apart from areas that required smaller slabs, such as curves or angles into taxi ways etc.
Whereas, a "round" area, such as a "frying pan" dispersal, would need to have some sections shorter than the "average" slab dimensions, in order to create the circle, but still maintain the required strength and overall integrity of the "pan", hence the mix of square and rectangular slabs.
Having said all that, as my display base is only representing part of a circular "frying pan" dispersal, and not showing the outside curves, I thought it would be more appropriate to portray the slabs as they look on the base, rather than have the whole thing looking to "regular" and "model like" and, all being well, this should, I hope, be more apparent once the Mosquito in in place on the display base.