I was asked to restore one of these about six years ago, to match up with a WW1 Holt Tractor. I was told that it had been one of a pair used on the firing range at Foulness, and the other one had been restored and had gone to New Zealand. The one I started on was missing most of the 'Trail' and had no barrel. It just had the WW2 wheel hubs and spokes with no outer rims, which were fixed into a frame presumably to steady it when firing. I went down to Woolwich with some friends to see 'Spikes gun', The Curator was very obliging, and allowed us access to the library where we gained very useful information from an original 8" Howitzer handbook. I was able to fabricate the missing 'Trail' and original type wheels, but had to use a WW2 155mm howitzer barrel, original WW1 howitzer barrels are just not available these days! The Holt has since been sold, and strangely the buyer didn't want the gun, which I believe is still for sale.