Bit off topic but I thought I could put a 'then and now' picture up when I came across this photograph whilst I was looking for engine ones, it was taken in Taunton in 1915:
My picture of Holt tractor and gun taken at GDSF last week.
I've no idea if the tractors are the same but they look similar, sure someone will be able to elaborate. Interesting that this gun has a little dolly trailer in between.