Are we sure the photo of Ant shows Boulton's Ant? The proportions and wheel size don't look the same to me. The drawing of Boulton's Ant show a round top tank like Queen of the Forest. The photo on page 266, Figure 90, shows Queen of the Forest in the background looking much like the drawing. Two separate safety valves were common in earlier times, one was out of the drivers reach to 'prevent' the safety valve being held down by the driver.