Ok Dave,

i've been back out with the digital vernier calipers (not engineering quality) admittedly I was working from memory, a dangerous passtime at my age wink , but that was my recollection, from when I did a lot of measuring when we had the thin web ones.

The three off cuts I found from different masts, including non anodised section, all measured between 1.6 to 1.8 mm.